Applied Mechanics and Materials Vol. 901

Abstract: Bottom ash is a part of by-product from the municipal solid waste power plants which is always a wider problem for the urban and rural communities due to its disposal plants may cause serious environmental pollution. This work was focused on the residual heavy metal in an incinerator bottom ash from the municipal waste power plant placed in Nongkham district, Bangkok. Four bottom ash samples were obtained in 2017. After drying and grounding, the bottom ash samples were prepared to clear solution with the microwave digestion technique using nitric, hydrochloric and hydrofluoric acid under the heating program. The total residual heavy metals in the incinerator bottom ashes, such as lead, copper, zinc, and cadmium were determined by using flame atomic absorption spectrophotometer (FAAS) with deuterium background correction. The total concentration of lead, copper, zinc and cadmium were found in the range of 280.40-354.22mg kg^-1, 365.35-524.45 mg kg^-1, 1,527.25-2,074.34 mg kg^-1, and 0.48-1.02 mg kg^-1, respectively. The recovery of all metals was found in the range of 89.4-101.2% and the relative standard deviation (RSD) was to be 2.15-3.55 % (n=7). The concentration of zinc, copper, and lead was found high levels, while cadmium was low concentration. Heavy metals in solid waste material occur in different chemical forms and phases. The sample preparation based on the microwave digestion was successfully developed for the waste samples with a good reliability.

Abstract: The aim of this work is the improvement of mechanical properties of oil palm fiber (OPF) reinforced polylactic acid (PLA) composites by using sodium hydroxide (NaOH) treatment. NaOH concentrations (0 to 15 %wt.) and treatment times (0 to 30 min) were varied to determine the suitable condition for surface treatment of OPF. Aspect ratio (L/D) and the surface texture of OPF were investigated by using an optical microscope and scanning electron microscope (SEM), respectively. The result suggested that the most suitable condition for surface treatment of OPF was NaOH concentration of 10 %wt. at immersion time of 20 min. Aspect ratio and surface roughness of OPF increased after alkali treatment. For the effect of alkali treatment on the mechanical properties of the composite, it was evaluated by tensile and impact testings and SEM technique. The results showed that surface treatment with NaOH led to enhance mechanical properties of the composite due to improvement of interfacial adhesion.

Abstract: In this study, the quick dry properties of summer men’s T-shirts of different brands (Nike, Adidas, Laishilong and Columbia) in Hong Kong market were explored by analyzing the wicking behavior. Laishilong was found to be the best sample in terms of vertical wicking for both short and long period. For the Nike fabrics, the wicking rate in courses direction was better than that in wales direction, whereas the vertical wicking of front body for Adidas was better than the back body. By contrast, Columbia performed the poorest in terms of vertical wicking for long period. With the help of this study, the general wicking properties of men’s quick-dry sportswear in the market can be compared which provide some idea to the consumer for product selection.

Abstract: Nowadays, radioactive materials are being applied in medical imaging. Because humans cannot observe radiation, radiation detection materials are very important to humans. A scintillator is a material that can change gamma photons to visible photons. Good scintillators should have the following properties: high scintillation light yield, good energy resolution, and high density. In this work, the scintillation light yield property of CWO crystals was studied due to its interesting properties, such as high stopping power and low hygroscopicity. CWO crystals were compared with BGO crystals. From the results, it was found that the BGO crystals showed higher scintillation light yield value at 662 keV energy from ¹³⁷Cs radioactive source than the CWO crystals, resulting in better energy resolution value. The intrinsic light yield and loss parameters for both crystals are also presented in this work.

Abstract: This study evaluated the cooling properties of summer cooling towels of different brands by studying the liquid moisture management behavior. All the samples were found to provide a cooling effect at first contact after being wetted. The samples of Perfect Fitness showed the highest cooling effect followed, whereas N-rit, Cooldyxm and Ice Towel samples had the poorest cooling effect. Through this study, the general cooling effect of summer cooling towels in the market can be compared which provide some idea to the consumer for product selection.

Abstract: This research paper presents the analysis of factor lightning protection for photovoltaic power generation. The question of the safety of lightning protection systems in photovoltaic power generation, especially under severe weather conditions such as thunderstorms. Therefore, a simple model of a photovoltaic power generation was developed, which included the arrangement of a conventional photovoltaic panel. The effect of lightning is also simulated by the pattern of lightning currents. It is also found that the size of the panel mounting structure and the point of lightning conduction induce the induced voltage at the junctions of the photovoltaic panel. Based on the results of the impulse current analysis, the intensity of the lightning current is increasing rapidly. All these factors will be taken into consideration in order to design a protective system.

Abstract: A variety of living organisms have a potential to generate the electrical currents which are alternative resources of electric power. Plant organisms absorb light radiation and convert electromagnetic energy to chemical energy via photosynthetic process. An electrical power is also generated from this process. However, a few amounts of currents are generated in this system. In this experiment, plants under the hydroponic system are used for studying the generation of electric power. Different ratios of tap water and Hoagland’s solution were used as culture solution. The cathode and anode were used as electrode in this system. Bioelectric potentials and currents of each treatment are detected at fifteen day of the generating system. The results showed that plant system under solution containing a high Hoagland’s nutrient generated current density and power density higher than those of the system containing a low Hoagland’s nutrient. However, plant system under solution containing a low Hoagland’s nutrient showed higher voltage than those of the system containing a high Hoagland’s nutrient. Metal oxide nanoparticles, known as photo-catalyst in fuel cell, were added in the solution of culture system and analyzed for electric power density. The result presented that ZnO nanoparticles affected a different increase in power density depending on the ratios of tap water and Hoagland’s solution.

Abstract: It was found that slagging in high temperature zone is one of the major problems in the refinery, petrochemical, pulp and paper, and steel industries; especially in biomass and coal pulverized power plant. Slagging conditions are critical factors influencing reliability and availability on a biomass utility boiler. In this study, several types of slagging were collected for chemical analysis. It was revealed that the chemical composition and other properties of received slagging showed unique results based on the type of feedstock fuel materials.