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    Nitrate Removal Enhancement Using Pulse Electrolysis and Aluminum Electrode
    (2025-01-01)
    Suwannimit, Prapavit
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    ; ; ;
    Srirach, Pisan
    This work focuses on nitrate elimination from municipal wastewater by an electrochemical method with pulsed DC electrolysis. The performance of electroreduction of nitrate was investigated without alkaline electrolyte addition. The nitrate removal reactor was fabricated from acrylic and aluminum electrodes. The nitrate concentration was analyzed by the light absorption of the substance using UV-Vis spectroscopy. The precipitated compounds were determined by X-ray diffraction technique. The experimental results with 180 min treatment indicated the optimum condition for nitrate removal, which was carried out on the pulse frequency of 10 kHz, pulse width of 80%, and electric current density of 16 mA/cm<sup>2</sup>. This condition was able to eradicate nitrate up to 90.73% (4.3 mg/L) from an initial nitrate concentration of 46.0 mg/L with a nitrogen selectivity of 80.08%. Furthermore, the weight loss of aluminum anodes was as low as 0.8%. The main precipitation formed in the electrolyte cell was aluminum hydroxide.
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    Effects of Red and Blue LEDs Light on Growth and Development of Chrysanthemum Callus
    (2025-07-01)
    Boonprasop, Sorawit
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    Seatiew, Kanjana
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    Effects of LED illumination on callus induction from petals of Karaked and Scarlet chrysanthemums cultivated in MS medium supplemented with 2 mg/I NAA and 4 mg/l Kinetin, under white LED light (PPFD 30±2 µmol/m2/s) and red to blue light in the ratios 30:10, 40:15, and 30:3 (PPFD 50±2 µmol/m2/s) for 16 h. It was determined that a light ratio throughout 4 weeks culture period had no impact on the fresh weight of callus. Conversely, varying light proportions yield distinct callus dry weights. Upon evaluating cultivar parameters, it was determined that ‘Karaked’ exhibited more fresh and dry weight compared to the callus of the ‘Scarlet’. Analysis of Karaked’s callus showed that callus cultured under 30:3 red to blue LED light exhibited the largest concentrations of all photosynthetic pigments, the greatest levels of malondialdehyde (MDA) and total phenolic compounds, and the lowest EC<inf>50</inf> value for DPPH free radical inhibition. In the case of the Scarlet chrysanthemum, following 8 weeks of callus induction, it was observed that a light ratio of red to blue at 40:15 yielded the maximum concentrations of chlorophyll a and carotenoids. No statistical difference was seen in the quantity of chlorophyll b. The MDA content of Scarlet’s callus cultivated under white LED light was the highest, and the EC<inf>50</inf> value for DPPH free radical inhibition was also the highest. Callus produced under red to blue LED light ratios of 30:10, 40:15, and 30:3 exhibited greater quantities of phenolic compared to callus cultured under white LED light.
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    Capacitive measuring of crude palm oil-water mixture
    (2017-12-13)
    Sriphant, Pongsakun
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    Srongprapa, Anupong
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    Oil palm is one of the famous commercial crops of Thailand. The production is in the 3<sup>th</sup> rank of the south east Asia, and plantation is still increasing every year. To investigate the feasibility of using electrical capacitance measuring technique as an alternative method for low-cost non-destructive, oil palm fresh oil (CPO) and water have been prepared and studied. One group is concerned with the immiscible fluid and another is all ultrasonic shakes. The mass concentration (x) of CPO varied from 0 g/cm<sup>3</sup> to 0.9 g/cm<sup>3</sup> and then all experiments were tested on room temperature (25<sup>o</sup>C). Guard parallel structure has been used in conjunction with AD7747 capacitive to digital converter to obtain capacitance value (y). The results show that y = 0.11987x<sup>2</sup> - 0.46104x + 0.47418 with r<sup>2</sup> = 0.98098. The model for second sample is y = 0.08965x<sup>2</sup> - 0.41335x + 0.3731 with r<sup>2</sup> = 0.9554. The capacitance of first sample is higher than the second sample. As previously mentioned, this project aims to make benefit of interest on seasonable optimistic harvests.
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    High-performance flexible thermoelectric generator based on silicone rubber and cover with graphite sheet
    (2024-01-05)
    Gobpant, Jakrit
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    ; ; ;
    Junlabhut, Prasopporn
    Harvesting thermal energy through a flexible thermoelectric generator (FTEG) offers an excellent micro-power solution for energizing node sensors in the realm of Internet of Things (IoT) and wearable electronics. Nonetheless, current FTEG suffer from drawbacks including low efficiency, significant thermal resistance, and complex manufacturing procedures. In this study, a high-performance FTEG using silicone rubber was designed and fabricated using a straightforward process. The finite-element method was used to optimize the copper electrode thickness, and the bendable substrate layers with various thermal conductivity were studied for the first time. The copper electrode thickness of 0.1 mm was selected because it offers high flexibility and bendability while still providing a relatively high-power output. The 5 × 5 cm<sup>2</sup> FTEG device was fabricated and covered with a bendable substrate. Silicon rubber (0.08 Wm<sup>−1</sup>K<sup>−1</sup>), silicon rubber added 5% graphene (0.14 Wm<sup>−1</sup>K<sup>−1</sup>), and graphite sheets (15 Wm<sup>−1</sup>K<sup>−1</sup>) were used as bendable substrates. The FTEG cover with graphite sheets has a maximum output voltage of 1.1 V under a temperature difference (ΔT) at 65 °C. Its maximum output power is 162.4 mW, corresponding to a power density of 6499.1 µW/cm<sup>2</sup> under the same above ΔT. The experimental findings indicated that integrating a bendable substrate with high thermal conductivity and electrical insulation properties enhances the performance of the FTEG.
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    Personal Identification using the Distance and Triangle between the Metacarpophalangeal Joints
    (2022-01-01)
    Srathongkao, Siwa
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    Ngamsapmanee, Wanasanan
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    Sawangjit, Nalita
    Personal identification using the distance among the metacarpophalangeal joints (MCPs) was presented in this study. The system was developed to specify the dorsal hand patterns. Firstly, the dorsal hand images were taken for the subjects via an infrared camera. Secondly, the dorsal hand images were converted to grayscale and binary images using image processing techniques. After that, the distance of the MCPs was measured by various the dorsal hand images including index to middle, middle to ring, ring to little, and index to little of the dorsal hand. In addition, the triangle areas between index to middle, middle to ring, ring to little, and index to little of the dorsal hand were used to specify the dorsal hand patterns. The result of the distance and the triangle area of the MCPS can be used to identify a person because of the difference of distance and the triangle area of the MCPs of each person.
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    Optimizing Waste Heat Conversion: Integrating Phase-Change Material Heatsinks and Wind Speed Dynamics to Enhance Flexible Thermoelectric Generator Efficiency
    Flexible thermoelectric generators (FTEGs) have garnered significant attention for their potential in harnessing waste heat energy from various sources. To optimize their efficiency, FTEGs require efficient and adaptable heatsinks. In this study, we propose a cost-effective solution by integrating phase-change materials into FTEG heatsinks. We developed and tested three flexible phase-change material thicknesses (4 mm, 7 mm, and 10 mm), focusing on preventing leaks during operation. Additionally, we investigated the impact of wind speed on the output performance of FTEGs with a flexible phase-change material heatsink. The results indicate that the appropriate flexible phase-change material thickness, when integrated with considerations for wind speed, demonstrates remarkable heat-absorbing capabilities at phase-change temperatures. This integration enables substantial temperature differentials across the FTEG modules. Specifically, the FTEG equipped with a 10 mm thick flexible phase-change material heatsink achieved a power density more than four times higher when the wind speed was at 1 m/s compared to no wind speed. This outcome suggests that integrating phase-change material heatsinks with relatively low wind speeds can significantly enhance flexible thermoelectric generator efficiency. Finally, we present a practical application wherein the FTEG, integrated with the flexible phase-change material heatsink, efficiently converts waste heat from a circular hot pipe into electricity, serving as a viable power source for smartphone devices. This work opens exciting possibilities for the future integration of flexible thermoelectric modules with flexible phase-change material heatsinks, offering a promising avenue for converting thermal waste heat into usable electricity.
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    Improving the photo-thermoelectric performance of CuAlO2 via doping with Bi
    (2021-12-01)
    Daichakomphu, Noppanut
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    Rodpun, Phumin
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    Pluengphon, Prayoonsak
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    Harnwunggmoung, Adul
    The photothermoelectric (PTE) effect enables the conversion of temperature differences induced by absorbed light to electrical voltages. For the first time, we investigated the effect of Bi doping on the photothermoelectric properties of CuAlO<inf>2</inf>. In this study, delafossite CuAl<inf>1-x</inf>Bi<inf>x</inf>O<inf>2</inf> (x = 0.01, 0.02, 0.03, 0.04, and 0.06) powders were synthesised. X-ray diffraction and X-ray absorption spectroscopy results indicated that the doping limit of Bi content was approximately 2.6–2.7 at% (x = 0.026–0.027). At x = 0.02, we successfully demonstrated the increase of electrical conductivity due to the reduced effective mass and the increased hole concentration, the increase of optical absorption due to the reduced band gaps, and lower thermal conductivity resulting from mass and strain fluctuations. At a Bi content of 2 at%, the photovoltage signals increased compared with the undoped CuAlO<inf>2</inf>. These results indicated that Bi doping could potentially improve the PTE properties of CuAlO<inf>2</inf>.
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    The uncertainty in sugar solution concentration measurement based on density approach
    (2013-11-04) ; ;
    The concentration of solution used in osmotic process is an important factor to dehydrate water from food, which is an effect to the rate of mass transfer. Therefore, the in line measurement and control of the concentration in osmotic process is taken into account. The density of sugar solution can be computed by volume and weight in order to determine the concentration in degree of Brix. This instrument will complete when accompanied by a statement of its uncertainty. The calibration equation established the relationship between the reading values of sensor and the values of concentration also need to clarify. The objective of this paper is to evaluate the uncertainty of predicted values of calibration equation; therefore, the uncertainty is determined in this study, and to compare the obtained results from the classical method in linear equation and the inverse method. Furthermore, the data from Monte Carlo simulations also are compared to the measured data. © (2013) Trans Tech Publications, Switzerland.
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    Kinetics of dye removal using Fe3O4 nanoparticles and pulsed white-LED illumination
    Removal of dyes with the aid of photocatalytic nanomaterials illuminated with continuous-light sources has been given substantial attention in the recent years. In the present work we study the efficiency of dye degradation using some alternative photocatalytic nanoparticles under condition of pulsed illumination. Our specific purpose is to investigate the removal of rhodamine 6G dye basing on suspended Fe<inf>3</inf>O<inf>4</inf> solution. The experiments are carried out in the batch mode when the effect of the exposition time (ranging from 30 to 150 min) on the dye removal is examined under both continuous and pulsed white-LED illuminations. Different pulsed-light frequencies and duty cycles are tested. We estimate the concentration of rhodamine 6G in the mixed solution following from its absorption spectrum measured with a UV-Vis spectrometer and determine in this manner the percentage of dye removal. Our main conclusion is that Fe<inf>3</inf>O<inf>4</inf> nanoparticles enable removing efficiently the rhodamine 6G dye under pulsed white-LED illumination. In particular, more than 90% of the dye is removed when the duty cycle is equal to 25% and the frequency to 30 kHz. The equilibrium state of this process is achieved in about 60 min.
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    Optimization of the nitrogen content for room temperature rapid synthesis of CuI thin films via liquid iodination method using Cu3N film as precursor
    (2020-06-01)
    Khumtong, Tanakorn
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    Chanlek, Narong
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    ; ;
    In this work, we demonstrate that CuI films can be obtained by the liquid–phase iodination method with the chemical reaction time only being 1 min between Cu<inf>3</inf>N and aqueous iodine solution at room temperature. This is a simple and eco-friendly method with high transparency and low resistivity. The Cu<inf>3</inf>N precursors were prepared by reactive DC magnetron sputtering using different N<inf>2</inf> partial pressures. The effect of nitrogen content of precursor (Cu<inf>3</inf>N) on the structural, electrical, and optical properties of CuI thin films was discussed. Electronegativity property was used to explain the growth mechanism of CuI films prepared by different nitrogen content in the precursor. By growing the CuI films with a N<inf>2</inf>:Ar gas ratio of 5:2, the average transmittance achieved was 75% in the visible spectral range, and the lowest resistivity achieved was 3.67 × 10<sup>–2</sup> Ω cm. These results suggest that the liquid iodination method using Cu<inf>3</inf>N film as precursor (N<inf>2</inf>:Ar gas ratio of 5:2) was suitable for preparing high-quality CuI films for application in transparent electronics.