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3D virtual intravascular endoscopy visualization of coronary artery plaques: Virtual intravascular endoscopy of coronary plaques
(2009-12-31)
Sun, Zhonghua
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Chaichana, Thanapong
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Dimpudus, Franky Jacobus
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Adipranoto, Jeffrey Daniel
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Nugroho, Johanes
The purpose of the study is to investigate the potential diagnostic value of 3D virtual intravascular endoscopy in the visualization of coronary artery plaques in patients with suspected coronary artery disease. Ten patients suspected of coronary artery disease undergoing 64-slice computed tomography scans were included in the study. Four main coronary artery branches including right coronary artery, left main stem, left anterior descending and left circumflex were assessed using virtual intravascular endoscopy with emphasis on the intraluminal appearance of coronary plaques (calcified and noncalcified plaques). Position of the plaques and degree of vessel stenosis was compared with 2D axial images in each patient. Coronary artery disease with >50% stenosis was found in 6 patients involving 7 left anterior descending and 3 right coronary artery branches. Left anterior descending branch was commonly affected with extensive calcification, while more than half of the right coronary arteries were involved with noncalcified plaques. Our results showed that virtual intravascular endoscopy provides unique information of the coronary plaques by demonstrating the intraluminal configuration of coronary plaques, position of the plaques in relation to the artery branches. Both calcified and noncalcified plaques can be identified on virtual endoscopy images. Further studies are needed to clarify the role of virtual intravascular endoscopy in the quantification of plaque volume, stratification of patients suffering from coronary artery disease and patients management. ©2009 IEEE.
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Measurement of linearity in THz-TDS
(2009-12-31)
Withayachumnankul, Withawat
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Ung, Benjamin S.Y.
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Fischer, Bernd M.
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Abbott, Derek
This article presents an approach to the measurement of the amplitude linearity in terahertz time-domain spectroscopy (THz-TDS) systems. The approach exploits a single wafer of high-purity float-zone silicon to produce multiple Fabry-Pérot reflections, which are stepwise attenuated and delayed. Comparison between the theoretical and experimental results can indicate a deviation in linearity. © 2009 IEEE.
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Hemodynamic effect of calcifed plaque on blood flow in carotid artery disease: A preliminary study - Hemodynamic effect of calcified plaque
(2009-12-31)
Sun, Zhonghua
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Mwipatayi, Bibombe
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Chaichana, Thanapong
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Ng, Curtise
The purpose of the study is to investigate the hemodynamic effect of calcified carotid plaque on blood flow in patients diagnosed with carotid artery disease. Two carotid artery models were generated based on a sample patient data, with normal and calcified carotid artery appearances. Circular calcified carotid plaque was found at the carotid bifurcation based on 3D computed tomography images. A computational fluid dynamics was performed to analyze the changes of blood flow in different situations. Our results showed that apparent turbulence was found in the diastolic phase at the carotid bifurcation in normal carotid artery geometry. In the presence of the calcified plaque, the flow velocity was increased to some extent, indicating the effect of plaque on hemodynamic changes. Wall shear stress was noticed to decrease at the aortic branches, and this indicates the potential risk of developing stenosis at this area. Our preliminary study demonstrates fluid structure interaction between calcified plaque and artery in terms of flow changes and wall shear stress. ©2009 IEEE.
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Biomass power generation development in Thailand
(2009-12-17)
Chai, Chompoo Inwai
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Chow, Chompoo Inwai
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Leelajindakrairerk, Monthon
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Banjongjit, Sulee
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Fuangfoo, Pradit
The emerging global warming crisis results from carbon dioxide emission has drawn an attention about renewable energy all over the world. Thailand is a developing country located at the heart of Southeast Asia with almost 70 million of population as of 2008. The ESI structure under the government of Thailand has been managed by the Electricity Generating Authority of Thailand (EGAT), Metropolitan Electricity Authority (MEA), and Provincial Electricity Authority (PEA) for almost 50 years. According to the Power Development Plan (PDP 2007), during the year 2007-2021, the government of Thailand plan to have the most economic power generation resources yet reliable and least environmental impact. To achieve those goals, there are three strategic plans which are to import power from neighboring country, to promote the renewable power generation from the public power companies, and to have a variety on power generations resources. This paper discusses the biomass power generation development in Thailand. System overview processes and biomass fuel consumed for the electricity production process are also presented. ©2009 IEEE.
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Thai emotion words analysis
(2009-12-28)
Yimngam, S.
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Premchaisawadi, W.
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Kreesuradej, W.
In a text-to-speech system, emotional expression is one of the most important factors for speech synthesis processing. There are many research projects that have attempted to develop a system which can read text, such as a novel, with emotion. Emotional expression makes a story come alive and catches the listeners' attention. Research on emotional expression usage in a Thai language text-to-speech synthesis has never been done before. This paper studies the classification of Thai emotional words by using interjection words defined in the Thai Royal Institute Dictionary (1999). This study makes a comparison between the words defined in the dictionary and a survey of annotators' opinion. The results show that the annotators' opinion of the emotional expression of the interjection words is significantly different from that defined in dictionary. Furthermore, these results indicate that there are many factors that have an effect on emotional expression such as sex, and age. Therefore, these factors should be utilized to identify emotional expressions in text for improving the efficiency of Thai text-to-speech development in the future. © 2009 IEEE.
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Discrete wavelet transform and back-propagation neural networks algorithm for fault classification on transmission line
(2009-12-16)
Pothisarn, C.
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Ngaopitakkul, A.
This paper proposes a technique using Discrete Wavelet Transform (DWT) and Back-Propagation Neural Network (BPNN) to identify the fault types on single circuit transmission lines. The ATP/EMTP is used to simulate fault signals. The mother wavelet daubechies4 (db4) is employed to decompose high frequency component from these signals. The variations of first scale high frequency component that detect fault are used as an input for the training pattern. The result has shown that the proposed technique gives satisfactory results.
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Design of optimal fuzzy logic-PID controller using bee colony optimization for frequency control in an isolated wind-diesel system
(2009-12-16)
Chaiyatham, T.
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Ngamroo, I.
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Pothiya, S.
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Vachirasricirikul, S.
Generally, the inevitable problems in the fuzzy logic-PID (FLPID) control design are the trial and error of the setting of scale factors, membership functions and control rules. To solve these problems, this paper proposes the optimal FLPID controller design using bee colony optimization (BCO) for the load frequency control in the microglia system. The considered microgrid is the hybrid wind-diesel isolated system. The BCO is applied to automatically optimize the FLPID controllers of governor in the diesel side and blade pitch control in the wind side. Simulation studies show the superior robustness of the optimal FLPID against system parameters variation in comparison with the optimal PID controller and the non-optimal FLPID controller.
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Robust frequency stabilization in a microgrid system
(2009-12-16)
Vachirasricirikul, S.
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Ngamroo, I.
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Kaitwanidvilai, S.
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Chaiyatham, T.
This paper proposes a new design of a robust control and monitoring system (RCMS) for robust stabilization of frequency fluctuation in a microgrid (MG) system. In MG system, the power sources consists of wind power (WP), photovoltaic (PV), microturbine (MT) and fuel cell (FC). Due to WP, PV and load fluctuations, the frequency stabilization of RCMS is performed by adjusting the power outputs of MT and electrolyzer system (ES) in both islanding and interconnected utility grid operations. The structure of MT and ES controllers is a proportional integral (PI). To enhance the robustness of designed controllers against system uncertainties, controller parameters of MT and ES are concurrently tuned by the particle swarm optimization based on a specified-structure H<inf>∞</inf> loop shaping control. Simulation results display the effectiveness and robustness of the proposed RCMS against system parameters variation and several operating conditions.
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Identification of the fault location for three-terminal transmission lines using discrete wavelet transforms
(2009-12-16)
Chiradeja, P.
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Pothisarn, C.
This paper proposes a technique to detect fault locations in a three-bus transmission system using discrete wavelet transform (DWT). The comparison among the first peak time in first scale of each terminal (buses) that can detect fault is performed and the two fastest first peak time obtained from comparison are used as an input data for traveling wave equation later. A comparison of results obtained from three different types of mother wavelet is discussed in order to identify the fault locations with an application of traveling wave theory. It is shown that the db4 mother wavelet produces better results than those from 'sym4' and 'coif4', with a mean error of less than 400 m.
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Toward fuzzy temporal databases with temporal fuzzy linguistic terms
(2009-12-11)
Soysangwarn, Sureeporn
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Chittayasothorn, Suphamit
Fuzzy databases have been proposed by many researchers for handling fuzziness in databases. Fuzzy linguistic terms are used instead of crisp values. They find applications in areas where exact or crisp values cannot always be obtained. In another database research area, temporal databases find applications where facts which are true in the past, as well as facts that will be true in the future are recorded together with current facts. There are also cases where fuzzy databases are also temporal. In most other works, fuzzy facts are temporal or the time itself is fuzzy. This paper presents the concept of a different fuzzy database where fuzzy linguistic terms are temporal. Sample queries and meta tables for temporal similarity degrees and temporal possibility distribution are also presented. ©2009 IEEE.

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