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Kampala A.,Rajamangala University of Technology at Tawan-ok | Horpibulsuk S.,Suranaree University of Technology | Chinkullijniwat A.,Suranaree University of Technology | Shen S.-L.,Shanghai JiaoTong University
Construction and Building Materials | Year: 2013

Reuse of waste materials for pavement applications is of great international interest. This paper presents basic and engineering properties of the recycled Calcium Carbide Residue (CCR) stabilized clay. Scanning electron microscopic images show that the recycled CCR stabilized clay particles are larger than the CCR and clay particles due to the attached pozzolanic products. The large grains reduce linear shrinkage and free swell ratio of the recycled CCR stabilized clay. For the same compaction energy and CCR content, the unit weight of the recycled CCR stabilized clay is lower than that of the CCR stabilized clay because the harder attached pozzolanic products resist the compaction. The strength development and the reduction in void ratio with time confirm that the pozzolanic reaction still prevails even after remolding. This implies that the pozzolanic reaction occurs mainly on the surface of the clay-CCR clusters. The remolding of CCR stabilized clay breaks down the cementitious bonds between the CCR-clay clusters and the unreacted CCR and clay particles in the clusters are then free to interact with water. The research outcome reinforces the possibility of using the recycled CCR stabilized clay as fill and pavement materials. The strength and resistance to compressibility are slightly lower than those of the original CCR stabilized clay for the same CCR content while the unit weight of recycled CCR stabilized clay is much lower, which reduces the overburden on the foundation. © 2013 Elsevier Ltd. All rights reserved. Source


Jantakun A.,Rajamangala University of Technology at Tawan-ok | Jaikla W.,King Mongkuts University of Technology Thonburi
Turkish Journal of Electrical Engineering and Computer Sciences | Year: 2013

The realization of 2 current-mode quadrature oscillators using current-controlled current differencing transconductance amplifiers (CCCDTAs) and grounded capacitors is presented. The proposed oscillators can provide 2 sinusoidal output currents with a 90° phase difference. They enable noninteractive dual-current control for both the condition of oscillation and the frequency of oscillation. The high-output impedances of the configurations enable the circuit to be cascaded without additional current buffers. The use of only grounded capacitors is ideal for integration. The circuit performances are depicted through PSpice simulations; they show good agreement to theoretical. © Tübi·tak. Source


Suebsuk J.,Rajamangala University of Technology at Tawan-ok | Horpibulsuk S.,Suranaree University of Technology | Liu M.D.,University of Wollongong
Computers and Geotechnics | Year: 2011

This paper presents a generalised critical state model with the bounding surface theory for simulating the stress-strain behaviour of overconsolidated structured clays. The model is formulated based on the framework of the Structured Cam Clay (SCC) model and is designated as the Modified Structured Cam Clay with Bounding Surface Theory (MSCC-B) model. The hardening and destructuring processes for structured clays in the overconsolidated state can be described by the proposed model. The image stress point defined by the radial mapping rule is used to determine the plastic hardening modulus, which varies along loading paths. A new proposed parameter h, which depends on the material characteristics, is introduced into the plastic hardening modulus equation to take the soil behaviour into account in the overconsolidated state. The MSCC-B model is finally evaluated in light of the model performance by comparisons with the measured data of both naturally and artificially structured clays under compression and shearing tests. From the comparisons, it is found that the MSCC-B model gives reasonable good simulations of mechanical response of structured clays in both drained and undrained conditions. With its simplicity and performance, the MSCC-B model is regarded as a practical geotechnical model for implementation in numerical analysis. © 2011 Elsevier Ltd. Source


Hussaro K.,Rajamangala University of Technology at Tawan-ok
American Journal of Environmental Sciences | Year: 2014

Hydrogen Sulfide (H2S, rotten-egg) is one of the major environmental pollutants having its sources in natural and anthropogenic activities. It's had smell gas produced by anaerobic digestion in acid condition from organic and inorganic compounds containing sulphur, presents dual problems of its toxicity and foul ordour. One of methods of its removal is adsorption. Activated carbon is a widely used adsorbent in the treatment of air pollution. Adsorption type and capacity are primarily based on the physical properties of pores, namely the surface area. Convetionnally, activated carbon is produced from biomass residues, wood coal and agricultural residuces. Today, one promising approach for the production of cheap and efficient activated carbon is used of waste from palm oil mill industries, which is palm oil shell. Palm oil shell is available in large quantities of approximately 0.53 million tonnes annually in Thailand. Palm oil shell is a by-products of the palm oil industry and was used as a raw material in this study due to its high carbon content, high density and low ash content. Normally, H2S in biogas, which is found the range between as low as about 50-10,000 ppm depending on the feed material composition to prodction, can cause corrosion to engine and metal substance via of SO2 from combustion. H2S must be removed from biogas product prior to further utilization. Therefore, in these research the usage of palm oil shell is especially important due to its high value added for produced activated carbon adsorbent for H2S adsorption in biogas product. In this study, fixed bed reactor (stainless steel with 54.1 mm internal diameter and 320 mm length) was studied to observe the effect of char product: Chemical agent ratio (Na2CO3 and ZnCl2, 1:1 to 1:3), which there are activated at 700°C activation temperature for 2 h on the chemical and physical properties, BET surface area, the pore volume, micropore volume and hydrogen sulfide adsorption. The result showed that the BET surface area, BET surface area, the pore volume and micropore volume increased progressively with increasing the char product: Chemical agent ratio. The value of maen total pore volume of activated carbon increased with an increased char product: Chemical impregnation agent ratio (Na2CO3 and ZnCl2) as is a 1:1 to 1:3, from 0.3743 to 0.4181 cc/g and 0.2877 to 0.3137 cc/g, respectively. The average micropore volume were 0.2224, 0.2411, 0.2270, 0.1721, 0.1686 and 0.1546 cc/g of AC_Na13, AC_Na12, AC_Na11, AC_Z13, AC_Z12 and AC_Z11, respectively. The results of yield, it was found that that the activated carbon for Na2CO3 agent is higher than activated carbon for ZnCl2 agent. The highest of yield was 32.3% for AC_Na13. Moreover, the maximum BET surface area and H2S adsorption was 743.71 m2/g and 247.33 ppm was obtained on AC_Na13. This gave H2S adsorption more than commercial activated carbon (1%). Guideline for evaluation chemically activated carbon for potential application were suggestd. The conclusion showed that AC_Na13 has good chemical and physical properties scuh as chemical content and surface area, which showed that the highest H2S adsorption (247.33 ppm). The carbon content and BET surface area of AC_Na13 were 78.76 (wt%) and 743.71 m2/g, respectively. Thus, chemical agent (Na2CO3) can be used effectively as an operating strategy to optimize surface area. The synthetices activated carbon with suggested BET surface area were is good agreement with those obtained with chemical activation by Na2CO3 impregnation. Moreover, activated carbon was used to the H2S removal, it is also for environment benefit in which air pollution by H2S emission and impact on human health could be potentially reduced. © 2014 Science Publication. Source


Boonchuay C.,Rajamangala University of Technology at Tawan-ok
IEEE Transactions on Power Systems | Year: 2014

In a new environment of energy deregulation, the locational marginal price (LMP) basis is overwhelming congestion management issues. But it still requires proper ancillary services to serve the system. Load frequency control (LFC) is needed to maintain the system frequency in the dynamic environment. In this letter, an efficient LFC approach with the critical load level (CLL)-based adaptive participation factor is proposed for an LMP-based market. The CLL is considered when the load varies from the generation set point. The proposed approach could enhance the LFC performance in securely following up the aggressive change of energy demand. The PJM 5-bus system is used to illustrate the proposed LFC. © 1969-2012 IEEE. Source

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