Applied Mechanics and Materials Vol. 804

Abstract: Water pollution comprises all of those compounds that change the quality of groundwater and surface water, therefore reducing the suitability of natural water for human use and other vital processes. These compounds result from human activities, especially those that are industrial, agricultural and domestic.The polyamide thin film composite reverse osmosis membranes become important in desalination of sea water and brackish water or waste water. However the polyamide reverse osmosis membranes tend to fouling due to their hydrophobic and rough surfaces. In this study flux and rejection of waste water from aluminum production industry were obtained during filtration process by using modified commercial composite membranes. Amount of fouling was evaluated with unmodified and modified membranes. Rejection of iron particles and PH of feed and permeate solutions were determined after filtration process. Results shows that modified membranes were performed higher metal ion rejection and antifouling performance than unmodified membranes.

Abstract: The objective of this study is to compare five forecasting statistical methods on the price of Jasmine rice. These methods are Simple Exponential Smoothing method, Holt’s method, Holt–Winter’s method, Box–Jenkins method and combined forecast based on regression method. All methods are tested on the data collection of the monthly series of the price of Jasmine rice from January 2007 to December 2012 recorded by the Bank of Thailand. By using the mean square error (MSE) and the mean absolute percent error (MAPE), the Holt’s method is the most promising method. In addition, Government and authorities should use this result for forecasting the price of Jasmine rice.

Abstract: We firstly present and analyze a feasible schematic optical sensor made from PANDA ring resonator which generates WGM of tunneling photons to be used in the atomic trapping process in quantum computer processing to teleport quantum states. A simulation done by launching electromagnetics of Gaussian soliton pulses into an optical tweezers device is given to obtain time dependent evolution of polarization qubit states. It shows that under very low temperature, an optimum photon resonant frequency of such qubit has sufficient stability lifetime to be used in quantum signal states transferring purposes.

Abstract: The aim of this study is to analyze the quantum correlation of entangled photons for four-wavemixing process within Kerr nonlinear susceptibility χ⁽³⁾ of an optical fiber ring resonator. The main system Hamiltonian composes of two types of coupling photon modes, including pumping and parametric-down conversion. Wigner representation is applied to the Heisenberg equation of motion derived from the system Hamiltonian in order to obtain the corresponding stochastic equations of motion in a c-number. Quantum trajectories obtained from the stochastic equation of motion of photon states are then derived. Finally, the entanglement inseparability criteria for a pair of entangled photonfrom a numerical approach is also satisfied.

Abstract: Preventing power transmission failures in its network of electrical terminal stations is a major concern for the infrastructure of the Thai capital Bangkok and its vicinity. Towards this objective the present study aims to analyse the network and its reliability under conditions of increased demand. The analysis is based on a representation of the network as a graph allowing to identify the most important terminal stations by graph-theoretical terms. These are, in particular, the centrality measures Degree Centrality (DC) giving the number of a station’s one-hop neighbours, Closeness Centrality (CC) describing the efficiency of power transmission from one station to others, shortest-path Betweenness Centrality (BC) indicating the number of a station’s occurrences on the shortest paths between indirectly connected stations, Hub describing stations that are connected to a large number of important stations, and Authority indicating the stations that connect many important stations. Experimental results revealed that the Bangkok Noi station was most significant when the measures DC, CC and BC were considered and, on the other hand, that the North Bangkok station was vital in terms of CC, Hub and Authority. Therefore, these stations need to be closely monitored and their operation to be carried out with extreme care in order to prevent the occurrence of power transmission failures within the Bangkok metropolitan area.

Abstract: This research studies the parameter identification for establish the model of inverter control system which has grid-connected in distributed power systems. Identification is a method of measuring the mathematical description of a system by processing the observed inputs and outputs of the system. The model developed is based on nonlinear autoregressive with exogenous input (NLARX) for simulate the inverter control system which has grid-connected in distributed power systems. To analyze the model, we use one, three and five steps ahead analysis technique which is the tool in mathematical model analysis for model categories of NLARX. In this research, we present comparative analysis of the model using NLARX in 3 different categories that is wavelet network, tree partition network and sigmoid network. The simulation results show that the optimal category of NLARX is sigmoid network which has one, three and five steps ahead value is equal to 97.01, 91.50 and 88.90 percent respectively from output model and the measured output from the validation data set from grid tied inverter mathematical modelling using genetic algorithm. This optimal model can be used to simulate for analyze trends of the output data which can represent for the real system.

Abstract: Fish cake is a popular cuisine among Thai people. However, the production process of pieces of raw fish cake still uses human labors so the production yield is quite low and it takes more consumption time. Moreover, the sizes of pieces of raw fish cake are not uniform. Therefore, the researchers aimed to design and construct a fish cake making machine to help improve the practical fish cake production process. The results showed that the fish cake making machine could manage raw fish cake into 20 even, round shaped pieces with a 50 mm diameter, 8 mm thickness within a minute. It required electrical power from an electric motor harboring 220 volt (AC), 60 watts, and speed at 28 rpm. The consumed electrical power was approximately 0.19 baht per hr. The results showed that with the qualification of fish cake making machine that can make several pieces of raw fish cake at the same size, the users satisfied it at least 70%. It is expected that more development of this fish cake machine will be tentatively worldwide applied in the food industry.

Abstract: Adaptive focus lens imitates human eye where the focal length differs, resulting from changes in its lens curvature. This study involved an investigation of a commercial adaptive lens, Optotune EL-10-30, a shape-changing lens in which the lens curvatures can be modified by applying different level of electric currents. The resulted focal lengths were measured at various supplied electric currents at various frequencies to find limitation of the lens by means of photography.

Abstract: Thai traditional computer keyboard layouts are derived from the Thai typewriter keyboard's layout, which supports typing with ten fingers. Hence, this layout is not optimized for typing on touch screen device with one finger. This article presents a new method in arrangement the position of Thai characters on the virtual keyboard to support typing by a single finger. The process of the new method consist of analysing Thai Language to create difference digraph table from Benchmark for Enhancing the Standard of Thai language processing corpus (BEST corpus), designed keyboard layout using evolutionary computation technique and estimated time speed of typing by model human hand movement with Fitts' Law. The experiment shows that new keyboard designed by the proposed method has achieved a typing speed faster than the Thai traditional keyboard layout.

Abstract: A solar chimney power plant is a simple solar thermal power plant that is capable of converting solar energy to thermal energy in the solar collectors. Then, the generated thermal energy is converted to kinetic energy in the chimney and ultimately to electric energy via a wind turbine and a generator. The purpose of this study is to evaluate the performance of the solar chimney power plant in Nakhon Ratchasima, Thailand in terms of estimateion for the electric energy output. A mathematical model based on the energy balance was developed to estimate the power output of solar chimneys as well as to examine the effect of various ambient conditions and structural dimensions on the power generation. It was found that, the wind speed inside chimney reaches more than 2 times of the value of free wind speed outside the chimney. The solar chimney power plant with 10 m chimney height and 4 m chimney diameter is capable of yearly producing between 1,779-3,647 W and the performance of solar chimney in the range of 9-18% respectively. The highest performance of solar chimney (18%) was appeared in April. It can save the use of conventional sources of energy like oil and natural gas.