Electricity capacity expansion in Thailand: An analysis of gas dependence and fuel import reliance

Electricity generation in Thailand is highly dependant on natural gas. Recent research has revealed that the Thai economy would become more vulnerable from high gas dependence in the power sector. This paper aims to assess the economic impact of gas dependence in power generation in the coming decades. To fulfil this objective, two scenarios of electricity capacity planning were developed and the results were analysed to understand the changes in gas dependence and the effects on import reliance. It is found that from 2011 to 2025, the average cost of natural gas for power generation will account for 2.41% of gross domestic product (GDP) while high oil price in international energy markets would push this cost to 2.97% of GDP. In addition, reliance on fuel imports for power generation, particularly natural gas and coal, is going to be another crucial concern to the security of energy supply as the costs of these imports during the planning horizon will increase significantly at an average rate of 6.78% per year.     

Extremely Enhanced Nonlinear Current–Voltage Properties of Tb‐Doped CaCu3Ti4O12 Ceramics

Nonlinear current–voltage properties of CaCu₃Ti₄O₁₂ ceramics were extremely enhanced by doping with Tb. Substitution of Tb to CaCu₃Ti₄O₁₂ resulted in a decrease in grain size due to the ability of Tb ions to inhibit grain boundary mobility. The dielectric properties of CaCu₃Ti₄O₁₂ ceramics were degraded after doping with Tb. Surprisingly, the nonlinear electrical properties were strongly enhanced. The best properties with a nonlinear coefficient of ~29.67 and breakdown electric field strength of ~1.52 × 10⁴ V/cm were obtained in the Ca_0.775Tb_0.15Cu₃Ti₄O₁₂ ceramic. These extremely enhanced properties were attributed to modification of grain boundary electrical response due to the effect Tb substitution.     

First-principles calculations and experimental study of enhanced nonlinear and dielectric properties of Sn4+-doped CaCu2.95Mg0.05Ti4O12 ceramics

High dielectric permittivity (ε′ ≈ 2000―6900) was accomplished in Sn⁴⁺-doped CaCu_2.95Mg_0.05Ti₄O₁₂ ceramics while retaining a low loss tangent (tanδ ≈ 0.027―0.075). Further, significant improvements in the nonlinear electrical properties, such as high values of the breakdown electric field (E_b ≈ 1.2―1.3 × 10⁴ V cm^?1) and nonlinear coefficient (α ≈ 31), were achieved. In addition, the nonlinear electrical parameters significantly improved, which is consistent with the increase in the electrical resistivities of the grains and grain boundaries due to the decrease in the Cu⁺/Cu²⁺ ratio. According to our first-principles calculations, the Sn atom at the Ti site prefers to be close to the Mg atom at the Cu site, while the oxygen vacancy prefers to be located at large distances from the Sn and Mg co-dopants. This confirms that the dielectric behavior and the nonlinear electrical properties originate from the interface between the grain and grain boundary.     

Modified giant dielectric properties of samarium doped CaCu3Ti4O12 ceramics

Effects of Sm³⁺ substitution on the microstructure and dielectric properties of CaCu₃Ti₄O₁₂ ceramics were investigated. The grain size of CaCu₃Ti₄O₁₂ ceramics was greatly decreased by doping with Sm³⁺, resulting from the ability of Sm³⁺ to inhibit the grain growth rate. This result can cause a decrease in the dielectric constant (?′) and loss tangent (tan δ) of CaCu₃Ti₄O₁₂ ceramics. Interestingly, high dielectric permittivity (?′ ～ 10,863) and low loss tangent (tan δ ～ 0.043 at 20 °C and 1 kHz) were observed in the Ca_0.925Sm_0.05Cu₃Ti₄O₁₂ ceramic. Nonlinear electrical properties of CaCu₃Ti₄O₁₂ ceramics were modified by doping with Sm³⁺. The dielectric relaxation behavior of Sm-doped CaCu₃Ti₄O₁₂ ceramics can be well ascribed based on the internal barrier layer capacitor model of Schottky barriers at the grain boundaries.     

An assessment of the potential for cool storage application in the Thai commercial sector

The potential for cool storage air-conditioning (CSA) has been assessed for the Thai commercial sector. Computer simulations of customer groups of electric utilities were performed to evaluate investment and electricity costs for a number of tariff cases. Field evaluations were performed through interviews with decision makers, using a multi-criteria decision method. The results confirm good potential for application of CSA.     

Making use of process tomography data for multivariate statistical process control

A novel strategy for making effective use of on‐line process tomography measurements for process monitoring is described. The electrical resistance tomography (ERT) sensing system equipped with sixteen electrodes provides 104 conductivity measurements every 25 ms. The data has traditionally been used for construction of images for display purpose. In this study, ERT data was used for multivariate statistical process control. Data at predefined normal operational conditions was processed using principal component analysis. The compressed data was used to derive two statistics, T² and squared prediction error (SPE). T² and SPE charts predict the probability that the process being monitored has undergone statistically significant changes from previous state or the so‐called normal operational state, in terms of mixing quality. The methodology is illustrated by reference to a case study of a sunflower oil/water emulsion process. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Effects of La3+ doping ions on dielectric properties and formation of Schottky barriers at internal interfaces in a Ca2Cu2Ti4O12 composite system

Influences of La³⁺ substitution on the dielectric properties and formation of Schottky barriers at internal interfaces of a Ca₂Cu₂Ti₄O₁₂ (CaTiO₃/CaCu₃Ti₄O₁₂) composite system were investigated. It was found that electrostatic potential barrier height was greatly reduced by doping with La³⁺, leading to a large decrease in the total resistance of internal interfaces between grains. This observation was attributed to the creation of conduction electrons, which were possibly induced by electrical charge compensation of La³⁺ substitution into Ca²⁺ sites. Variations in the dielectric properties of La³⁺-doped CaTiO₃/CaCu₃Ti₄O₁₂ composite ceramics and nonlinear properties can be described based on the electrical responses at the internal interfaces between CaCu₃Ti₄O₁₂–CaCu₃Ti₄O₁₂ grains and CaTiO₃–CaCu₃Ti₄O₁₂ grains. Influence of possible charge compensation due to different levels of La³⁺ dopant on the formation of potential barriers was discussed.     

Improved dielectric and non-ohmic properties of Ca2Cu2Ti4O12 ceramics prepared by a polymer pyrolysis method

Non-ohmic and dielectric properties of Ca₂Cu₂Ti₄O₁₂ (CaCu₃Ti₄O₁₂/CaTiO₃ composite) ceramics prepared by a polymer pyrolysis method (PP-ceramic samples) are investigated. The PP-ceramics show a highly dense structure and improved non-ohmic and dielectric properties compared to the ceramics obtained by a solid state reaction method (SSR-ceramic samples). ?′ (tan δ) of the PP-ceramic samples is found to be higher (lower) than that of the SSR-ceramic samples. Interestingly, the PP-ceramic sintered at 1050 °C for 10 h exhibits the high ?′ of 2530 with weak frequency dependence below 1 MHz, the low tan δ less than 0.05 in the frequency range of 160 Hz-177 kHz, and the little temperature coefficient, i.e., |Δ?′| ≤ 15 % in the temperature range from −55 to 85 °C. These results indicate that the CaCu₃Ti₄O₁₂/CaTiO₃ composite system prepared by PP method is a promising high-?′ material for practical capacitor application.     

Enhancement of giant dielectric response in Ga-doped CaCu3Ti4O12 ceramics

The influences of Ga³⁺ doping ions on the microstructure, dielectric and electrical properties of CaCu₃Ti₄O₁₂ ceramics were investigated systematically. Addition of Ga³⁺ ions can cause a great increase in the mean grain size of CaCu₃Ti₄O₁₂ ceramics. This is ascribed to the ability of Ga³⁺ doping to enhance grain boundary mobility. Doping CaCu₃Ti₄O₁₂ with 0.25 mol% of Ga³⁺ caused a large increase in its dielectric constant from 5439 to 31,331. The loss tangent decreased from 0.153 to 0.044. The giant dielectric response and dielectric relaxation behavior can be well described by the internal barrier layer capacitor model based on Maxwell?Wagner polarization at grain boundaries. The nonlinear coefficient, breakdown field, and electrostatic potential barrier at grain boundaries decreased with increasing Ga³⁺ content. Our results demonstrated the importance of ceramic microstructure and electrical responses of grain and grain boundaries in controlling the giant dielectric response and dielectric relaxation behavior of CaCu₃Ti₄O₁₂ ceramics.     

Firmness Properties of Mangoes

The purpose of this research was to determine the firmness of mango fruit at different stages of maturity. Immature, mature, and over mature fruit from two Thai mango cultivars (Nam Dokmai and Chok Anan) were subjected to two firmness measuring techniques: a slow compression technique using the Universal Testing Machine and a high-speed impact sensing technique using the low-mass impact tester. The firmness of a mango as determined by the compression test was expressed by the slope of the force-deformation graph, while firmness values derived from the impact test were defined by the ratio between maximum acceleration and the corresponding time (the firmness index). A very good correlation between the two indicators was obtained. Each firmness indicator of the two cultivars remained relatively unchanged from the immature through to the fully mature stage, although firmness rapidly decreased as the fruit ripened. The Chok Anan cultivar was firmer than the Nam Dokmai type throughout the development period. The impact method was able to determine mango firmness rapidly, accurately, and non-destructively.