A Cooperative Game Analysis of Transboundary Hydropower Development in the Lower Mekong: Case of the 3S Sub-basins

Hydropower development has enormous economic, environmental, and social impacts at a local, national, and trans-national level. It has been suggested that transboundary water conflicts, such as those that may arise from hydropower development, may be addressed through benefit sharing. This study attempts to investigate the net benefits of hydropower development and water resources utilization in transboundary sub-basin, the Sekong, Sesan and Srepok (commonly known as 3S) sub-basin, in the Mekong River Basin using a game theory approach. This study proposes a methodology for analyzing complex transboundary river-basin issues using the game theory concepts, such as core stability and incentive compatibility. A wide range of parameters have been incorporated to define models and methodologies, and an adaptation strategy for the area has been proposed. The results suggests that benefit sharing and cooperation among the riparian countries would lead to benefits to all. It is observed that the greater the cooperation, the higher is the total benefits. External funding and optimal usage of funds will also play a critical role in this context in the near future. The results of the study will provide a basis for local policy decisions and regional planning in the Mekong River and beyond.     

Chemorheology and thermomechanical characteristics of benzoxazine‐urethane copolymers

In this research, processability and some important thermomechanical properties of polybenzoxazine (BA‐a) modified with a highly flexible urethane elastomer (PU) are discussed. This copolymer has been reported to show synergy in its glass transition temperature and some mechanical properties thus provides a fascinating group of high temperature polymers with enhanced flexibility. The results reveal that a processing window of the BA‐a/PU mixtures is widened with the increasing urethane prepolymer fraction, that is, the liquefying temperature is lowered and the gel point shifted to higher temperature with the amount of the PU. Synergism in glass transition temperature (T_g) of this copolymer was clearly confirmed, i.e., T_g's of the BA‐a/PU alloys were significantly greater than those of the parent resins, i.e., BA‐a (T_g = 166°C) and PU (T_g = ? 70°C). In addition, flexural modulus was found to systemically decrease from 5.4 GPa of the neat polybenzoxazine to 2.1 GPa at 40% by weight of the PU. Flexural strength of the alloys also shows a synergistic behavior at the BA‐a/PU ratio of 90/10. Coefficient of thermal expansion of the polymer alloys were also found to show a minimum value at BA‐a/PU = 90/10. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

New computer geometric modeling approach with filament assembly model for two-ply yarns structures

This article presents a new computer geometric modelling approach for three-dimensional of two-ply yarn structures with filament assembly model. The geometric of individual filaments in two-ply yarn structures with uncompressed and compressed states were studied. In the uncompressed state the filaments in ply yarns have the form of coaxial double wound helices; we simulate the paths of these filaments in the ply yarns. In the compressed state the transformation of the initial filament distribution from the uncompressed state into the distribution after compression by a transverse force. The ply yarns cross-section uses the concept of virtual locations to simulate the filament distributions. Each cross-section is rotated along the single yarn and the ply yarn length. The curve of each filament in each two successive cross-sections is approximated by NURBS and then each curve is created by sweeping a closed curve along the centerline of the single yarn and ply yarn path. The method described is demonstrated in the uncompressed and compressed state of two-ply yarns by the CAD model using geometric parameters of the double-rove acrylic-fiber yarns. The simulation using this approach can demonstrate more realistic and improved visual simulations of real two-ply yarns.     

Synthesis and characterization of anatase photocatalyst powder from sodium titanate compounds

The synthesis of anatase photocatalyst powder from sodium titanate compounds prepared from rutile and sodium carbonate powder was studied. The sodium titanate compounds were derived from the solid-state reactions of three different (1:4, 1:1.58 and 1:0.73) (m/m) ratios of TiO₂:Na₂CO₃ at 850 °C. Then, the powder was dissolved in 5 M H₂SO₄ solution, filtered, washed, dried and calcined at 400, 500 or 600 °C for 2 h. The effects of processing parameters on the resultant phase structure, crystallite size, morphology and the surface area of the synthesized powders were investigated. It was found that the anatase powder with a crystallite size of about 102 nm and a specific surface area of 16.7 m²/g synthesized from sodium titanate compounds with a 1:1.58 (m/m) ratio of TiO₂:Na₂CO₃ and calcined at 600 °C showed the best photocatalytic activity to degrade of methylene blue in aqueous solution under UV irradiation.     

Control of paralleled single-phase motors for a crop chopping machine

This article proposes a fuzzy control system for driving multiple single-phase induction motors in parallel connection. The drive system employs only a single PWM inverter controlled by a self-organizing fuzzy controller. This drive and control system has been utilized in an invented crop chopping machine. The article presents the control system concept, modeling of multiple motors in parallel connection, controller design, simulation of the closed-loop system and practical results. The control system stability is also analyzed on the basis of passivity theorem.     

Improvement of polyimide/polysulfone composites filled with conductive carbon black as positive temperature coefficient materials

In this study, polyimide (PI)/polysulfone (PSF) blends filled with carbon black (CB) were developed for the use as positive temperature coefficient (PTC) materials in order to achieve the volume resistivity as lower than 10⁴ Ω.cm at room temperature. The weight ratios of PI/PSF were various from 100/0 to 10/90 with CB varied from 0 to 20 wt%. The use of conductive filler was reduced when PSF was blended with PI; the blends clearly possessed a percolation threshold decreased by 90%. The electrical conductivity of the CB-filled blends was higher than those of CB-filled pure PI. The transition temperature for PTC material was reported in the range of 180 to 210 °C. The preferential location of CB filler in PI domains could be observed using the optical microscope. In addition, the composites met the standards for the obtained mechanical and thermal properties, exhibiting the potential use as PTC materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48482.     

Quantitative evaluation of cleaner production and environmental policy toward the co-benefit of greenhouse gas and odor reduction: case study of Tapioca starch industry

Chemical components of airborne volatile organic compounds (VOCs) released from a wastewater treatment system of the tapioca industry were identified. Quantitative analysis of the concentrations and the emissions of each chemical were evaluated taking into consideration the difference in atmospheric turbulence over the surface of the wastewater during the day and the nighttime periods. The chamber experiments were performed on-site in order to reflect actual environmental characteristics of the study area. Chemical concentrations were analyzed following the U.S. EPA TO-15 Standard Method. Emissions of each compound were calculated using the box model scheme. It was found that acetaldehyde and acetone were two major compounds of released airborne VOCs from the wastewater treatment system of the tapioca industry. Due to its high organic content, the wastewater treatment facilities of this type of factory generally caused the odor problem to its surrounding communities. These data were then used to evaluate the success of implementing the Clean Development Mechanisms project in this industry. Reduction in the affected area from odor by improving the wastewater treatment system from opened lagoons which is the type of common practice in most of the tapioca factories in the developing countries to the modified covered lagoons was evaluated. These results supported the theory of the co-benefit of managing both local environmental problems and reduction of greenhouse gas emissions from the implementation of cleaner technology in the agro-industry. This methodology can be applied to reveal and quantify the success of other green efforts particularly in the agro-industry businesses.

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Incident-angle-modulated molecular plasmonic switches: a case of weak exciton-plasmon coupling

We have designed an angularly tunable plasmonic system that consists of Au nanodisks in combination with molecules of photoswitchable resonance, spiropyran, to gain new insights into weak exciton-plasmon couplings. In the weak exciton-plasmon coupling regime, switching molecular resonance can induce localized surface plasmon resonance (LSPR) peak shifts due to the change in the refractive index of the molecular materials. On the basis of the angle-resolved spectroscopic study of the nanodisk-spiropyran system both with and without UV irradiation, we reveal an unusual "zigzag" curve for the LSPR peak shifts (due to the photoswitching of the molecular resonance) as a function of the original LSPR peak wavelength. A further theoretical analysis attributes the "zigzag" curve to two significant competing effects that depend on the incident angle of the probe light: plasmon-enhanced molecular resonance absorption and LSPR sensitivity to the surroundings' refractive index.     

Preparation of chemical vapor sensing materials from composites of esterified poly(vinyl alcohol) and carbon black

Poly(vinyl alcohol) was modified by esterification to prepare poly(vinyl alcohol) copolymers. The degree of esterification on poly(vinyl alcohol) was elucidated by FTIR, ¹H NMR, and elemental analysis. The obtained products were poly(vinyl benzoate)-co-poly(vinyl alcohol) (B-PVA) and poly(vinyl p-toluoate)-co-poly(vinyl alcohol) (P-PVA). The chemical vapor sensors were fabricated by the mixtures of polymer and carbon black in dimethyl sulfoxide and their subsequent preparation as thin films onto the interdigited electrodes by the application of the spin-coating technique. The chemical vapor sensing properties of the sensors were examined with various solvents, such as hexane, toluene, methanol, ethanol, isopropanol, tetrahydrofuran, ethyl acetate, acetonitrile, dimethyl sulfoxide, and water. The experimental results indicated that modifying the chemical structure of PVA results in the decreased polarity of the obtained products. The composites of modified PVA consequently responded well to low polarity solvents, such as THF or ethyl acetate.