Entity

Time filter

Source Type

Tainan, Taiwan

Chen C.-K.,NCKU
CMES - Computer Modeling in Engineering and Sciences | Year: 2010

Up to now, solving some nonlinear differential equations is still a challenge to many scholars, by either numerical or theoretical methods. In this paper, the method of the maximum principle applied on differential equations incorporating the Residual Correction Method is brought up and utilized to obtain the upper and lower approximate solutions of nonlinear heat transfer problem of the non-Fourier fin. Under the fundamental of the maximum principle, the monotonic residual relations of the partial differential governing equation are established first. Then, the finite difference method is applied to discretize the equation, converting the differential equation into the mathematical programming problem. Finally, based on the Residual Correction Method, the optimal solution under the constraints of inequalities can be obtained. The methodology of incorporating the Residual Correction Method into the nonlinear iterative procedure of the finite difference will make it easier and faster to obtain upper and lower approximate solutions and can save the computing time, reduce the storage of memory and avoid unnecessary repeated testing. Copyright © 2010 Tech Science Press. Source


Cheng F.-T.,National Cheng Kung University | Tsai W.-H.,NCKU | Wang T.-L.,Slovak University of Technology in Bratislava | Yung-Cheng Chang J.,Soochow University of Taiwan | Su Y.-C.,University of the East in Philippines
IEEE Robotics and Automation Magazine | Year: 2010

This work presents an advanced e-manufacturing model with four core components: the MES, EES, SC, and EC. The definitions, missions, primary issues, and the corresponding implementation frameworks associated with these four components are described and surveyed. Each component plays a pivotal role in the advanced e-manufacturing model. The MES improves productivity and yield, the EES enhances OEE, the SC shortens the O2 cycle, and the EC reduces the T2M cycle time. With e-manufacturing, overall capabilities including productivity, yield, and OEE of the complete production platform can be improved, and the T2M and O2D cycles can be shortened. Furthermore, the goals of agility, efficiency, and decision making for the entire semiconductor manufacturing processes can be improved. We believe that e-manufacturing will accomplish all the missions of SMA and generate competitiveness in the global business environment. © 2006 IEEE. Source


Hu W.-C.,Institute of Computer and Communication Engineering | Yu D.-F.,Institute of Computer and Communication Engineering | Jiau H.C.,NCKU
Proceedings - 5th International Conference on Software Engineering Advances, ICSEA 2010 | Year: 2010

When people involve with software more in their daily lives, software companies must provide services through handling various operating questions that users request in the forums. However, different from conventional software companies, various types of difficulties, propositions and opinions could be issued by open source software users in addition to the operating questions. These difficulties, propositions and opinions are generally referred as questions in the forums. The questions, as valuable knowledge of the open source project, should be systematically managed. To manage the questions, a common strategy is to construct a FAQ in open source projects. The FAQ can reduce the volume of similar questions in the forums and prevent active forum members from wasting time on answering questions which are already handled before. Most previous literature focuses on existing FAQ retrieval instead of finding and constructing FAQ. This study, as a pioneering work, proposes a configurable and semi-automatic FAQ finding process to assist forum managers in constructing the FAQ. Also, two case studies are conducted to evaluate the effectiveness of the proposed FAQ finding process. © 2010 IEEE. Source


News Article | January 2, 2016
Site: http://www.techtimes.com/rss/sections/science.xml

The disappearance of electrons in Earth's atmosphere that has puzzled scientists for the past 50 years may finally be understood after researchers at the Massachusetts Institute of Technology (MIT) discovered evidence of what could very well be the cause of this phenomenon. During a presentation at the American Geophysical Union's (AGU) annual meeting last month, MIT atmospheric electrician Earle Williams and his colleagues explained how particles of meteor dust found high above Earth may be absorbing the electrons in the planet's atmosphere. This, in turn, creates what they describe as a "D-region ledge," where the concentration of electrons rapidly drops. Williams said that physicists have long been baffled by the missing electrons, and had considered every possible explanation for the phenomenon they could come up with, from clouds of ice flying high above Earth to electrically charged clusters of water. In their study, Williams described the location of the D-region ledge as "the most dramatic gradient" part of the ionosphere. He said it is highly conspicuous and it needs to be better understood. Electrons in the atmosphere are produced when ultraviolet (UV) rays from the sun come into contact with atoms of nitric oxide. However, scientists have noticed that since the 1960s, there has been a significant drop in the concentration of electrons found in the atmosphere during nighttime. This sudden decrease in electrons was discovered when rockets where sent into the upper atmosphere to measure its electron density, temperature and pressure. Researchers believe this "electron ledge" typically occurs within the D-layer of the ionosphere, which can be found between 37 miles and 56 miles above the surface of Earth. The D-region ledge is often used as part of modern communication. While the portion of the ionosphere located above the ledge is known to conduct electricity, the electron-depleted area below the ledge does not allow the passage of electromagnetic waves. Electron-depleted air found below the ledge serves as an insulator, which allows radio waves and electromagnetic waves between the ground and the atmosphere to circle the world. Scientists have yet to determine why the D-region ledge is in the atmosphere, but they believe it is most visible at night and that it can be observed equally above the poles of Earth, the equator and even in other parts of the planet. Cracking The Case Of The Missing Electrons According to Williams and fellow researcher, Joanne Wu, of the National Cheng Kung University (NCKU) in Taiwan, they have considered various prevailing hypotheses that could help them understand the nature of the D-region ledge, but they were not able to find one they could use. One of these hypotheses suggests that ice clouds could be the ones absorbing the electrons in the atmosphere. However, ice clouds are known to form mostly in high altitudes whereas the D-region ledge can be found equally prominent in different parts of Earth. The researchers then came across an earlier study featured in the Journal of the Atmospheric Sciences that described another part of the atmosphere known as the sodium layer, which is formed from the fine dust particles of meteoroids. The findings of the study point to how space rocks traveling through the upper atmosphere become heated when they interact with molecules of oxygen and nitrogen. These rocks then collide with other atoms as they continue to penetrate the atmosphere, causing them to become hot enough to reach boiling point. It is at this point in which atoms of sodium are detached from the meteoroid. Williams and his colleagues considered these findings in their search for a possible explanation for the D-region ledge. The team's new theory involves having minerals in meteoroids, such as silicon and iron, boil off in order to form a cloud of dust and smoke. The atoms of these minerals would then collide with the atoms of nitrogen and oxygen in Earth's atmosphere, causing free electrons from the atoms of silicon and iron to be knocked off. These electrons would then form glimmers of faint light too small to be visible to the naked eye. The dust from the meteor would combine with the free electrons that came about after the UV rays from the sun interacted with Earth's atmosphere. It is believed that the D-region ledge is more prominent at night because the sun's UV radiation is 100 times more powerful during the day, causing the free electrons produced at daytime to minimize the effect of the ledge. Williams said that if their theory is correct, these actions could form a thick layer of dust, which could then descend gradually to Earth as a result of gravity. The dust particles that end up on the planet's surface are so small that they are barely detectable. The researchers' theory has it that the D-region ledge occurs 53 miles above Earth because the distance corresponds to the part of the atmosphere where meteoroids often burn up upon entry. Ionospheric physicist Morris Cohen of the Georgia Institute of Technology, who is not involved in the current study, said the theory posited by Williams and his colleagues is plausible as there are numerous circumstantial evidence to support it. Cohen, however, argued that it will be difficult to test the theory directly because the part of the atmosphere described in the MIT study is not easily accessible. "It's too high to reach with balloons, and it's too low to hit with satellites," Cohen said.


Liang S.-F.,National Cheng Kung University | Kuo C.-E.,NCKU | Hu Y.-H.,NCKU | Pan Y.-H.,Ledder Technologies Holdings Ltd. | Wang Y.-H.,Society of Streams
IEEE Transactions on Instrumentation and Measurement | Year: 2012

In this paper, we propose an automatic sleep-scoring method combining multiscale entropy (MSE) and autoregressive (AR) models for single-channel EEG and to assess the performance of the method comparatively with manual scoring based on full polysomnograms. This is the first time that MSE has ever been applied to sleep scoring. All-night polysomnograms from 20 healthy individuals were scored using the Rechtschaffen and Kales rules. The developed method analyzed the EEG signals of C3-A2 for sleep staging. The results of automatic and manual scorings were compared on an epoch-by-epoch basis. A total of 8480 30-s sleep EEG epochs were measured and used for performance evaluation. The epoch-by-epoch comparison was made by classifying the EEG epochs into five states (Wake/REM/S1/S2/SWS) by the proposed method and manual scoring. The overall sensitivity and kappa coefficient of MSE alone are 76.9% and 0.65, respectively. Moreover, the overall sensitivity and kappa coefficient of our proposed method of integrating MSE, AR models, and a smoothing process can reach the sensitivity level of 88.1% and 0.81, respectively. Our results show that MSE is a useful and representative feature for sleep staging. It has high accuracy and good home-care applicability because a single EEG channel is used for sleep staging. © 2012 IEEE. Source

Discover hidden collaborations