Kaewkhao J.,Nakhon Pathom Rajabhat University |
Limsuwan P.,King Mongkut's University of Technology Thonburi
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2010
In this work, the mass attenuation coefficients, partial interactions and the effective atomic numbers (Zeff) of Bi2O3, PbO and BaO in xRmOn:(100-x)P2O5 (where x=30≤x≤ 70 (% by weight)) glass system have been investigated on the basis of the mixture rule at 662 keV. The total and partial interactions were calculated by WinXCom software. It has been found that the total mass attenuation coefficients of glasses increase with increasing Bi2O3 and PbO concentrations, due to the increasing photoelectric absorption in glass samples. However, Compton scattering gives dominant contribution to the total mass attenuation coefficients for the studied glass samples. The Zeff increases with increase in Bi2O3, PbO and BaO concentrations. For comparison, the Zeff of PbO glasses are comparable to that of Bi2O3 glasses and Zeff of both glasses are greater than BaO glasses. These results are very useful for designing radiation shielding glass and reflecting the influence of bismuth, barium, and lead content in radiation shielding phosphate glass. Besides the mentioned usefulness of the new materials, development of lead-free radiation protecting glass also leaves non-toxic impact on our environment. Copyright © 2009 Published by Elsevier B.V. All rights reserved.
Nathao C.,King Mongkut's University of Technology Bangkok |
Sirisukpoka U.,Nakhon Pathom Rajabhat University |
Pisutpaisal N.,King Mongkut's University of Technology Bangkok
International Journal of Hydrogen Energy | Year: 2013
Anaerobic digestion is an attractive process for generation of hydrogen and methane, which involves complex microbial processes on decomposition of organic wastes and subsequent conversion of metabolic intermediates to hydrogen and methane. Comparative performance of a sequential hydrogen and methane fermentation in two stage process and methane fermentation in one stage process were tested in batch reactor at varying ratios of feedstock to microbial inoculum (F/M) under mesophilic incubation. F/M ratios influence biogas yield, production rate, and potential. The highest H2 and CH4 yields of 55 and 94 mL g-1 VS were achieved at F/M of 7.5 in two stage process, while the highest CH4 yield of 82 mL g-1 VS in one stage process was observed at the same F/M. Acetic and butyric acids are the main volatile fatty acids (VFAs) produced in the hydrogen fermentation stage with the concentration range 10-25 mmol L-1. Little concentrations of VFAs were accumulated in methane fermentation in both stage processes. Total energy recovery in two stage process is higher than that in one stage by 18%. This work demonstrated two stage fermentation achieved a better performance than one stage process. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Chanthima N.,Nakhon Pathom Rajabhat University |
Kaewkhao J.,Nakhon Pathom Rajabhat University
Annals of Nuclear Energy | Year: 2013
The radiation shielding parameters of (50 - x)SiO2: 15B 2O3: 2Al2O3: 10CaO: 23Na 2O: xBi2O3 glass systems (where x = 0, 5, 10, 15 and 20 mol%) were theoretically calculated using WinXCom program. The characteristics of radiation shielding parameters for the glass systems of different bismuth compositions were found to be dependent on energy regions. At low-energy region, the radiation shielding parameters show several discontinuous jumps correspond to photoelectric absorption edges. At medium-energy region, the radiation shielding parameters are almost constant and the effective atomic number is close to the mean atomic number, dominated by Compton scattering process. In high-energy regions, pair production becomes the main interaction process and tends to be constant over energy. The mean free paths of the glasses were compared with several standard shielding concretes and it had been shown with lower values of MFP (from 10 MeV to 100 GeV) than serpentite, odinary, chromite, ferrite and barite except for the glass systems with 0 and 5 mol% of Bi2O3. The investigation was carried out to explore the advantages of the glass systems in radiation shielding applications. © 2012 Published by Elsevier Ltd. All rights reserved.
Flood-hazard assessment and risk-based zoning of a tropical flood plain: Case study of the Yom River, Thailand [Evaluation du danger dinondation et zonage basé sur le risque dans une plaine dinondation tropicale: Cas de la Rivière Yom, Thaïlande]
Tingsanchali T.,Nakhon Pathom Rajabhat University |
Hydrological Sciences Journal | Year: 2010
This study contributes to the comprehensive assessment of flood hazard and risk for the Phrae flood plain of the Yom River basin in northern Thailand. The study was carried out using a hydrologic-hydrodynamic model in conjunction with a geographic information system (GIS). The model was calibrated and verified using the observed rainfall and river flood data during flood seasons in 1994 and 2001, respectively. Flooding scenarios were evaluated in terms of flooding depth for events of 25-, 50-, 100- and 200-year return periods. An impact-based hazard estimation technique was applied to assess the degree of hazard across the flood plain. The results showed that 78% of the Phrae flood-plain area of 476 km2 in the upper Yom River basin lies in the hazard zone of the 100-year returnperiod flood. Risk analyses were performed by incorporating flood hazard and the vulnerability of elements at risk. Based on relative magnitude of risk, flood-prone areas were divided into low-, moderate-, high- and severe-risk zones. For the 100-year return-period flood, the risk-free area was found to be 22% of the total flood plain, while areas under low, medium, high and severe risk were 33, 11, 28 and 6%, respectively. The outcomes are consistent with overall property damage recorded in the past. The study identifies risk areas for priority-based flood management, which is crucial when there is a limited budget to protect the entire risk zone simultaneously. © 2010 IAHS Press.
Singh V.P.,Karnatak University |
Badiger N.M.,Karnatak University |
Chanthima N.,Nakhon Pathom Rajabhat University |
Kaewkhao J.,Nakhon Pathom Rajabhat University
Radiation Physics and Chemistry | Year: 2014
Gamma-ray exposure buildup factor (EBF) values and neutron shielding effectiveness of bismuth borosilicate (BBS) glass systems in composition (50-x)SiO2:15B2O3:2Al2O3:10CaO:23Na2O:xBi2O3 (where x=0, 5, 10, 15 and 20mol%) were calculated. The EBF values were computed for photon energy 0.015-15MeV up to penetration depths of 40mfp (mean free path) by the geometrical progression (G-P) method. The EBF values were found dependent upon incident photon energy, penetration and bismuth molar concentration. In low- and high-energy photon regions, the EBF values were minimum whereas maximum in the intermediate-energy region. The fast neutron removal cross sections for energy 2-12MeV were calculated by the partial density method. The BBS glass with 20mol% Bi2O3 is found to be superior gamma-ray and neutron transparent shielding. The EBF values of the BBS glasses were compared with steel-magnetite concrete and lead. The investigation was carried out to explore the advantages of the BBS glasses in different radiation shielding applications. © 2013 Elsevier Ltd.
Janjai S.,Nakhon Pathom Rajabhat University
Procedia Engineering | Year: 2012
A number of students who are educated to be primary and secondary school teachers still have problems in designing lesson plans. In this research, an instruction model for improving the ability of students in designing the lesson plans was developed. The instruction model was based on the theories of constructivism and metacognition. The research activities consist of 4 steps as follows. Firstly, a learning unit was created by using the backward design approach. Secondly, an instruction model was designed by employing the theories of constructivism and metacognition. Based on this instruction model, the lesson plans of the learning units were prepared for teaching the students. Thirdly, 18 students of Nakhon Pathom Rajabhat University were taught by using this instruction model for one semester. Finally, the ability in designing the lesson plans of these students were evaluated. The evaluation was based on the achievement of the study and the quality of the lesson plans produced by these students. It was found that the ability in designing the lesson plans of the student after being taught by using this instruction model was significantly improved. In addition, the lesson plans obtained from 33.3%, 50.0% and 16.7% of the total students were evaluated to be in the very good, good and moderate levels, respectively. © 2010 Published by Elsevier Ltd.
Tingsanchali T.,Nakhon Pathom Rajabhat University
Procedia Engineering | Year: 2012
Flood impact is one of the most significant disasters in the world. More than half of global flood damages occur in Asia. Causes of floods are due to natural factors such as heavy rainfall, high floods and high tides, etc., and human factors such as blocking of channels or aggravation of drainage channels, improper land use, deforestation in headwater regions, etc. Floods result in losses of life and damage properties. Population increase results in more urbanization, more impervious area and less infiltration and greater flood peak and runoff. Problems become more critical due to more severe and frequent flooding likely caused by climate change, socio-economic damage, population affected, public outcry and limited funds. Flood loss prevention and mitigation includes structural flood control measures such as construction of dams or river dikes and non-structural measures such as flood forecasting and warning, flood hazard and risk management, public participation and institutional arrangement, etc. This paper describes concepts, policy, plan and operation on integrated urban flood disaster and risk management. In most developing countries, flood disaster management activities are handled by government. Participation of nongovernmental agencies and private sectors are very limited. Activities are exercised rather independently without proper coordination or integration. Flood disaster management in developing countries is mostly reactive responding to prevailing disaster situations (emergency response and recovery). Reactive response should be changed to proactive response to increase effectiveness of management and reduce losses of life and properties. Proactive disaster management requires more participation from various governments, non-governmental and private agencies and public participation. It involves more effort and time, more budget, equipments, facilities and human resources which leads to integration of flood disaster management for both long term and short term activities. Strategic framework on integrated flood disaster management includes four cyclic steps namely: 1) preparedness before flood impact such as flood forecasting and warning; 2) readiness upon flood arrival; 3) emergency responses during flood impact and; 4) recovery and rehabilitation after flood impact. Examples on urban flood disaster and risk management in Thailand are illustrated and discussed. Conclusions and recommendations for further improvement are provided. © 2010 Published by Elsevier Ltd.
Sripanya W.,Nakhon Pathom Rajabhat University
Advanced Studies in Theoretical Physics | Year: 2013
Magnetometric resistivity is an electromagnetic exploration method that has been used successfully to investigate electrical conductivity structures within the earth. We derive an analytical solution of the steady state magnetic field due to a direct current semi-infinite source on a multilayered earth with a layer having exponentially varying con- ductivity. Our variation in conductivity is realistic and can be gen- eralized to all cases of exponential profiles. The Hankel transform is introduced to our problem and analytical result is obtained. Our so- lution is achieved by solving a boundary value problem in the wave number domain and then transforming the solution back to the spatial domain. An inverse problem via the use of the Levenberg-Marquardt optimization technique is introduced for finding the conductivity pa- rameters of the ground. The optimal result of our model is close to the true value with percentage errors of our two conductivity parameters less than 2.6% and 3.6% after using only 3 iterations. © 2013 Lhachmi El Badri et al.
Thongleam T.,Nakhon Pathom Rajabhat University
IEEE Region 10 Annual International Conference, Proceedings/TENCON | Year: 2016
In this work, the low-voltage current feedback operational amplifier (CFOA) with bulk-driven, quasi-floating-gate (QFG) transistor and bulk-driven-quasi-floating-gate (QFG) transistor techniques to operate under low supply voltage is proposed. The proposed circuits were design based on the voltage follower and current follower while the output stages are designed base on the voltage follower. The CFOA circuits are designed by using the 0.18 μm CMOS technology and supply voltage operated 1 V. Simulation results shows output impedance of CFOA with bulk-driven, quasi-floating-gate (QFG) MOS transistor and bulk-driven-quasi-floating-gate (BD-QFG) MOS transistor are 55.72 ΩdB, 43.88 ΩdB, and 41.63 ΩdB, respectively. Finally, the proposed BD, QFG and BD-QFG MOS transistors techniques can used before the ultra-low voltage and low-power CFOA circuits. © 2015 IEEE.
Phuengrattana W.,Nakhon Pathom Rajabhat University
Nonlinear Analysis: Hybrid Systems | Year: 2011
In this paper, we prove weak and strong convergence theorems for Ishikawa iteration of Suzuki-generalized nonexpansive mappings in uniformly convex Banach spaces. Furthermore, we extend the results to CAT(0) spaces. Our work extends the results of Suzuki [T. Suzuki, Fixed point theorems and convergence theorems for some generalized nonexpansive mapping, J. Math. Anal. Appl. 340 (2008) 1088-1095] and Takahashi and Kim [W. Takahashi, G.E. Kim, Approximating fixed points of nonexpansive mappings in Banach spaces, Math. Jpn. 48 (1998) 1-9]. © 2011 Elsevier Ltd.