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Khamsawang S.,King Mongkut's University of Technology Thonburi | Wannakarn P.,Rajamangala University of Technology at Phra Nakhon | Jiriwibhakorn S.,King Mongkut's University of Technology Thonburi
2010 The 2nd International Conference on Computer and Automation Engineering, ICCAE 2010 | Year: 2010

This paper proposes an improved approach based on conventional particle swarm optimization (PSO) for solving an economic dispatch(ED) problem with considering the generator constraints. The mutation operators of the differential evolution (DE) are used for improving diversity exploration of PSO, which called hybrid particle swarm optimization - differential evolution (PSO-DE). The mutation operators are activated if velocity values of PSO nearly to zero or violated from the boundaries. Four scenarios of mutation operators are implemented for PSO-DE. The simulation results of all scenarios of the PSO-DE outperform over the PSO and other existing approaches which appeared in literatures. ©2010 IEEE.

Newman P.A.,University of Toronto | Lee S.-J.,University of California at Los Angeles | Roungprakhon S.,Rajamangala University of Technology at Phra Nakhon | Tepjan S.,University of Toronto
Prevention Science | Year: 2012

High HIV prevalence among men who have sex with men (MSM) and transgender women in Thailand suggest a vital need for targeted interventions. We conducted a cross-sectional survey to examine and compare sexual risk behaviors, and demographic and behavioral correlates of risk, among MSM and transgender women recruited from gay entertainment venue staff and community-based organization (CBO) participants. We used venue-based sampling across nine sites in Bangkok and Chiang Mai. Among 260 participants (57. 3% gay-identified, 26. 9% heterosexual/bisexual-identified, 15. 8% transgender; mean age = 26. 7 years), nearly one-fifth (18. 5%) reported unprotected anal sex (UAS), half (50. 4%) sex in exchange for money, and one-fifth (20. 0%) STI diagnosis (past year). Nearly one-fourth (23. 1%) reported oral erectile dysfunction medication use and nearly one-fifth (19. 2%) illicit drug use (past 3 months). Overall, 43. 1% indicated that healthcare providers exhibited hostility towards them. Gay entertainment venue staff were significantly more likely to self-identify as heterosexual/bisexual (versus gay or transgender female), and to have less than high school degree education, higher monthly income, to have engaged in sex in exchange for money, sex with women and unprotected vaginal sex, but were significantly less likely to have engaged in UAS than CBO participants. Targeted interventions for younger MSM and transgender women, for non gay-identified men, and strategies to address structural determinants of risk, including low education and discrimination from healthcare providers, may support HIV prevention among MSM and transgender women, and serve broader national HIV prevention efforts in Thailand. © 2012 Society for Prevention Research.

Cameron M.P.,University of Waikato | Newman P.A.,University of Toronto | Roungprakhon S.,Rajamangala University of Technology at Phra Nakhon | Scarpa R.,University of Waikato | Scarpa R.,University of Technology, Sydney
Vaccine | Year: 2013

This paper estimates the marginal willingness-to-pay for attributes of a hypothetical HIV vaccine using discrete choice modeling. We use primary data from 326 respondents from Bangkok and Chiang Mai, Thailand, in 2008-2009, selected using purposive, venue-based sampling across two strata. Participants completed a structured questionnaire and full rank discrete choice modeling task administered using computer-assisted personal interviewing. The choice experiment was used to rank eight hypothetical HIV vaccine scenarios, with each scenario comprising seven attributes (including cost) each of which had two levels. The data were analyzed in two alternative specifications: (1) best-worst; and (2) full-rank, using logit likelihood functions estimated with custom routines in Gauss matrix programming language. In the full-rank specification, all vaccine attributes are significant predictors of probability of vaccine choice. The biomedical attributes of the hypothetical HIV vaccine (efficacy, absence of VISP, absence of side effects, and duration of effect) are the most important attributes for HIV vaccine choice. On average respondents are more than twice as likely to accept a vaccine with 99% efficacy, than a vaccine with 50% efficacy. This translates to a willingness to pay US$383 more for a high efficacy vaccine compared with the low efficacy vaccine. Knowledge of the relative importance of determinants of HIV vaccine acceptability is important to ensure the success of future vaccination programs. Future acceptability studies of hypothetical HIV vaccines should use more finely grained biomedical attributes, and could also improve the external validity of results by including more levels of the cost attribute. © 2013 Elsevier Ltd.

Chansuvarn W.,Rajamangala University of Technology at Phra Nakhon | Panich S.,Rajamangala University of Technology at Phra Nakhon | Imyim A.,Chulalongkorn University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

(Chemical Equation Presented) A new and simple spectrophotometric method has been developed and validated for measuring the contamination of melamine in different milk products. The method is based upon measuring the absorption of the complex formed from melamine, 4-hydroxyacetophenone (Hap) and 1-pyrene carboxaldehyde (Pcd), which was adapted from the Mannich reaction. Quantitative analysis was done at a wavelength of 236 nm within a few minutes. The reaction was optimized by focusing on both obtaining high performance of the method and to concern the volatility and toxicity of used reagents. This method provided a linear dynamic range, limit of detection and limit of quantification of 0.100-3.78, 0.08 and 0.14 mg L-1, respectively. The relative standard deviation (RSD) was 3.6% (n = 10). The recoveries of melamine spiked liquid milk samples, with melamine concentrations of 0.63, 1.26, 1.89 and 2.52 mg L-1, were 87.7 ± 3.7%, 91.1 ± 8.8%, 89.2 ± 4.4% and 90.6 ± 3.6% (n = 3), respectively. © 2013 Elsevier B.V. All rights reserved.

Chansuvarn W.,Rajamangala University of Technology at Phra Nakhon | Tuntulani T.,Chulalongkorn University | Imyim A.,Chulalongkorn University
TrAC - Trends in Analytical Chemistry | Year: 2015

This review focuses on colorimetric and visual assays for determination of mercury(II) (Hg2+) ions based on gold nanoparticles (AuNPs), fluorescent gold nanoclusters (AuNCs), gold nanorods (AuNRs), gold nanoflowers (AuNFs) and gold nanostars (AuNSs). The analytical colorimetric approaches based on AuNPs can be categorized according to the aggregation or disaggregation mechanisms of functionalized or unmodified AuNPs. The colorimetric concept involves change of the color of a solution of AuNPs from deep red to purple or blue. Disaggregation assays involve reversing the color from blue to red. Detection using AuNCs is based on Hg2+-induced fluorescence quenching of functionalized AuNCs and label-free AuNCs. The benefits of these systems are simplicity, rapidity, cost-effective production, ease of usage, easy visualization of the color change, and detection using spectrophotometry, fluorometry and the naked eye. We summarize applications to real samples, limits of detection, and the development of test strips. © 2014 .

Rukzon S.,Rajamangala University of Technology at Phra Nakhon | Chindaprasirt P.,Khon Kaen University
Materials and Design | Year: 2012

This paper presents the use of bagasse ash (BA) as a pozzolanic material for producing high-strength concrete. Portland cement type I (PC) is partially replaced with finely ground bagasse ash. The concrete mixtures, in part, are replaced with 10%, 20% and 30% of BA respectively. In addition, the compressive strength, the porosity, the coefficient of water absorption, the rapid chloride penetration and the chloride diffusion of concretes are determined. The test results indicate that the incorporation of BA up to 30% replacement level increases the resistance to chloride penetration. Besides, the use of 10% of BA produced concretes with good strength and low porosity. Reasonably, the substitution of 30% BA is acceptable for producing high-strength concrete. © 2011 Elsevier Ltd.

Chindaprasirt P.,Khon Kaen University | Chotetanorm C.,Khon Kaen University | Rukzon S.,Rajamangala University of Technology at Phra Nakhon
Journal of Materials in Civil Engineering | Year: 2011

This paper presents the use of palm oil fuel ash as a pozzolanic material in producing high-strength and high-workability concrete. Portland cement Type I (CT) was partially replaced with ground palm oil fuel ash (PA). PA with 2-5% by weight retained on a sieve No. 325 was used. The concrete mixtures were made with portland cement Type I containing 10, 20, and 30% of PA. Compressive strength, coefficient of water absorption, rapid chloride penetration and corrosion resistance of concretes were determined. Test results indicated that the high-strength high-workability concrete can be achieved by using PA to replace portland cement Type I up to 20%. The resistance to chloride-induced corrosion of concrete containing PA as measured by accelerated corrosion test with impressed voltage is significantly improved in comparison to that of CT concrete. © 2011 American Society of Civil Engineers.

Rukzon S.,Rajamangala University of Technology at Phra Nakhon | Chindaprasirt P.,Khon Kaen University
International Journal of Minerals, Metallurgy and Materials | Year: 2013

This article presents a study on the resistance to chloride penetration, corrosion, porosity, and strength of mortar containing fine fly ash (FA), ground rice husk-bark ash (RB), and ground bagasse ash (BA). Ordinary Portland cement (CT) was blended with a single pozzolan and two pozzolans. Strength, porosity, rapid chloride penetration, immersion, and corrosion tests were performed to characterize the mortar. Test results showed that the use of ternary blends of CT, FA, and RB or BA decreased the porosity of the mortar, as compared with binary blended mortar containing CT and RB or BA. The resistance to chloride penetration of the mortar improved substantially with partial replacement of CT with FA, RB, and BA. The use of ternary blends of CT, FA and RB or BA produced the mortar with good strength and resistance to chloride penetration. The resistance to chloride penetration was higher with an increase in the replacement level due to the reduced calcium hydroxide. © University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg 2013.

Rukzon S.,Rajamangala University of Technology at Phra Nakhon | Chindaprasirt P.,Khon Kaen University
Journal of Materials in Civil Engineering | Year: 2010

This paper presents a study of the strength and carbonation resistance of mortar made with portland rice husk ash cement by some accelerated short-term techniques in 5% carbon dioxide. Three finenesses of rice husk ashes, vizoriginal rice husk ash (RAO), medium rice husk ash (RA1) with 15-20% by weight retained on a sieve No. 325, and fine rice husk ash (RA2) with 1-3% by weight retained on a sieve No. 325. Ordinary portland cement was partially replaced with RAO, RA1, and RA2. Compressive strength, porosity, and carbonation depth were determined. The result indicated that the RA2 decreased the water requirement to a lesser extent as compared to that of the RA1 and RAO. The use of RA2 produced mixes with good strength and low porosity of mortar. The carbonation depth increased with an increase in the replacement level for all rice husk ashes. The carbonation depth of RA2 was lower than those of RA1 and RAO. The carbonation depth increased with a decrease in compressive strength and with an increase in amount of water requirement. © 2010 ASCE.

Prabpayak C.,Rajamangala University of Technology at Phra Nakhon
Kasetsart Journal - Natural Science | Year: 2015

Let K be an algebraic number field, OK its ring of integers. An order O in K is a subring of OK which contains a Z -basis for the field K. The conductor of O is the largest ideal of OK contained in O. This paper showed that Z + f is the only one order in quadratic number fields having conductor ideal and conductor ideals were characterized in a Galois extension over Q. © 2015, Kasetsart University. All rights reserved.

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