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Estimation of Atmospheric Precipitable Water in Thailand using an Artificial Neural Network
Get PDF In this work, an Artificial Neural Network (ANN) was proposed to estimate monthly average precipitable water (PW) using ambient air relative humidity, ambient air temperature, saturated water vapour pressure and the order of the month as input data. The PW data measured from ground-based sunphotometer were used as output data. The multilayer perceptron ANN using the back propagation training algorithm with two hidden layers was employed for deriving the PW. A five-year period (2009-2013) of the data collected from four meteorological stations, namely Chiang Mai (18.98°N, 98.98°E), Ubon Ratchathani (15.25°N, 104.87°E), Bangkok (13.67°N, 100.60°E) and Songkhla (7.20°N, 100.60°E) were used to train the ANN. An independent two-year period (2014-2015) of the data from the same stations were used to evaluate the performance of the trained ANN model. The result shows that PW at the four stations derived from the ANN agrees well with those obtained from the measurement, with the discrepancy in terms of root mean square error (RMSE) and mean bias error (MBE) of 7.5% and -0.1%, respectively.
Keywords: precipitable water, artificial neural network, back propagation algorithm  
Impact of Adjustable External Horizontal Shading Slats on Indoor Visual Comfort in Tropical Climate
Get PDF The main function of windows is to provide natural light and a view of the outdoor surroundings. Excessive direct sunlight penetrating into interior spaces through the windows poses glare and contrast problems in addition to excessive beam solar radiation which leads to high cooling loads. Shading slats are installed to block beam radiation and enhance the general visual environment for building occupants. Despite their proven energy saving potential, building designers tend to shun these shading devices for reasons such as maintenance costs, aesthetics, glare possibility and their interference of occupants’ view of the outdoor surroundings. In this paper the impact of adjustable external horizontal shading slats on occupants’ visual comfort and view was investigated. Full scale experiments were conducted under the dynamic tropical climate of Thailand. Annual simulations using full-year weather records were undertaken for a model room for cases of north and south facing windows to establish appropriate monthly slat adjustment angles that block undesired direct sunlight while guaranteeing the maximum possible view of exterior surroundings. Window luminance and work plane illuminance levels were examined and compared with proposed thresholds for comfortable working environments from previous studies. Lighting energy consumption and savings were also investigated in comparison to windows with heat reflective glass, commonly preferred by building designers. The study showed that it is possible to save 40% to 60% of energy consumed by electric lamps, avoid glare and achieve a comfortable workspace with a good view of exterior surroundings for most of the year by use of adjustable external horizontal shading slats.
Keywords: free view fraction, external horizontal slats, glare, energy savings
The Transition from Conventional Energy to the Photovoltaic Systems and its Struggle under the Dominant Electricity Regime in Thailand
Get PDF Electricity in Thailand has been heavily dependent on fossil-based fuels, and centrally controlled by the government and associated technocrats. Global issues, such as Cold War, oil and financial crises, along with environmental concerns, have considerably affected the dominant electricity regime of Thailand and driven it towards seeking renewable sources of energy for electricity generation. Photovoltaics, despite its high potential as a sustainable source of electricity, however, remains a supplementary production in the existing electricity regime, not the future electricity transition. In this study, archival data, interviews, and case studies had been analyzed and it was found that the photovoltaic systems in Thailand accounted for only 2.6% of the nation’s total capacity in 2014 while the number is expected to rise to only 8.5% in 2036. Using the Multi-Level Perspective (MLP) concept from the system innovation transition theory, this study explained why photovoltaics cannot be developed into a dominant source of electricity in Thailand. This study also discovered that the development of photovoltaics at the niche level the electricity regime’s existing governance, technology, centralized production and distribution, supply and demand chains of commercial appliances, and culture of the electricity users are not supportive of the photovoltaic systems. Therefore, without significant technological breakthrough and sincere commitment to energy reforms, the photovoltaic systems will continue to struggle and cannot become a major element of the future electricity transition in Thailand.
Keywords: Multi-Level Perspective, Landscape change, Thai electricity regime, Photovoltaic
Comparison of Lead Zirconate Titanate Properties between the Pressing Process and the Gel Casting Process by using Ethylene Glycol Diglycidyl Ether (EGDGE) Epoxy Resin as a Gelling Agent
Get PDF Gel casting has been widely developed during the past ten years due to its applicability in the complex shape fabrication of small ceramic products such as transducers and sensors, and this process provides a low-cost manufacturing route. The purpose of this research is to focus on the PZT properties resulting from the pressing and gel casting processes. In the pressing process, a soft PZT 5H powder was pressed using an Instron testing machine under 90 MPa. In the gel casting process, the ethylene glycol diglycidyl ether (EGDGE) epoxy monomer and a solution of an ammonium salt of an acrylic polymer in water (NH4PAA) were utilised as a gelling agent and dispersant, respectively. The results showed that the viscosity of the PZT was minimised by adding 1.2 wt% of the dispersant. The highest green strength of approximately 35 MPa was found from the pressed sample. In the gel casting process, at 40 wt% EGDGE resin content and 46 vol% solids loading provided the highest green strength of approximately 30 MPa. The PZT samples from both processes were sintered at 1,200 °C. The sample from the pressing process provided the highest values of d33, kp and εr of approximately 590 pC/N, 0.62, and 2,875, respectively; while the PZT samples fabricated from a gel casting slurry incorporating a 40 wt% EGDGE resin and 46 vol% solids loading provided d33, kp and εr values of approximately 575 pC/N, 0.6, and 2800, respectively. The results indicated that the desired properties of the pressed PZT sintered samples were slightly higher than those of the properties of the PZT gel cast samples.
Keywords: PZT, Piezoelectric, Dielectric, EGDGE Epoxy Resin, Gel Castin
Adsorption of Methylene blue onto Cajeput Tree Bark: Isotherm and Kinetic Studies
No full text Cajeput tree bark was used as a low-cost adsorbent for the removal of methylene blue from aqueous solutions. The effects of pH, contact time and initial methylene blue concentration on adsorption capacity were studied in batch experiments. The experimental results indicated that the optimum pH for methylene blue adsorption was 7 and the adsorption equilibrium was achieved within 90 minutes. Equilibrium adsorption data were analyzed using Langmuir and Freundlich isotherms. The Langmuir isotherm fitted the equilibrium data better than the Freundlich isotherm. The maximum monolayer adsorption capacity of cajeput tree bark was found to be 64.43 mg/g. The pseudo-first-order and pseudo-second-order kinetic models were selected to describe the adsorption mechanism. Kinetic studies revealed that the adsorption kinetics of methylene blue followed the pseudo-second-order kinetic model. These results showed that cajeput tree bark can be used as an efficient low-cost adsorbent for the removal of methylene blue from aqueous solutions.
Keywords: Adsorption, Methylene blue, Cajeput tree bark, Langmuir isotherm, Freundlich isotherm, Adsorption kineti
Microplastic Contaminations in Buffet Food from Local Markets
Get PDF Microplastics are environmental problems at global level, which can be primary environmental risks associated with food contaminations. Therefore, this study aims at determining contamination of microplastics in buffet food at three local markets in Ayutthaya and Pathum Thani, Thailand. This research investigated the contamination of microplastics in buffet food at three fresh markets. The results found the highest contamination 16 pieces/5g of tissue (wet weight) from mussel and fish tofu samples. The evaluation of consumption was consuming 1 kilogram of food could receive 3,200 microplastics of contamination that representing 13.01% from 11 types of microplastic. Moreover, the microplastic contamination also found the highest level in seafood (833+159 pieces/1 kg of tissue). Approximate 40.65% of the food products from the delicatessen type and products from meat were contaminated the microplastic by average 30.89% and 28.46%, respectively. Most microplastic contamination shad blue color and consisted of multiple types of microplastic, including fibers, fragments, microbeads, rods and pellets, respectively. Consequently, the presence of microplastics in buffet food especially in seafood should be concern about the potential effect of microplastics on human health, impact on food safety and socio economic wellbeing. This research obtained data that will be useful for consumers to consider options of the buffet food and to reduce health risk in long–term.
Keywords: microplastic, buffet food, food contamination, plastic packaging, plastic