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Lin Y.-C.,Japan National Institute of Advanced Industrial Science and Technology | Komsa H.-P.,P.O. Box 11100 | Yeh C.-H.,National Tsing Hua University | Bjorkman T.,P.O. Box 11100 | And 8 more authors.
ACS Nano | Year: 2015

Rhenium disulfide (ReS2) and diselenide (ReSe2), the group 7 transition metal dichalcogenides (TMDs), are known to have a layered atomic structure showing an in-plane motif of diamond-shaped-chains (DS-chains) arranged in parallel. Using a combination of transmission electron microscopy and transport measurements, we demonstrate here the direct correlation of electron transport anisotropy in single-layered ReS2 with the atomic orientation of the DS-chains, as also supported by our density functional theory calculations. We further show that the direction of conducting channels in ReS2 and ReSe2 can be controlled by electron beam irradiation at elevated temperatures and follows the strain induced to the sample. Furthermore, high chalcogen deficiency can induce a structural transformation to a nonstoichiometric phase, which is again strongly direction-dependent. This tunable in-plane transport behavior opens up great avenues for creating nanoelectronic circuits in 2D materials. © 2015 American Chemical Society.

Lin Y.-H.,National Taiwan Normal University | Liang J.-C.,Graduate Institute of Applied Science and Technology | Tsai C.-C.,National Taiwan University of Science and Technology
American Journal of Physiology - Advances in Physiology Education | Year: 2012

The purpose of this study was to investigate students' conceptions of and approaches to learning science in two different forms: internet-assisted instruction and traditional (face-to-face only) instruction. The participants who took part in the study were 79 college students enrolled in a physiology class in north Taiwan. In all, 46 of the participants were from one class and 33 were from another class. Using a quasi-experimental research approach, the class of 46 students was assigned to be the internetassisted instruction group, whereas the class of 33 students was assigned to be the traditional instruction group. The treatment consisted of a series of online inquiry activities. To explore the effects of different forms of instruction on students' conceptions of and approaches to learning science, two questionnaires were administered before and after the instruction: the Conceptions of Learning Science Questionnaire and the Approaches to Learning Science Questionnaire. Analysis of covariance results revealed that the students in the internet-assisted instruction group showed less agreement than the traditional instruction group in the less advanced conceptions of learning science (such as learning as memorizing and testing). In addition, the internet-assisted instruction group displayed significantly more agreement than the traditional instruction group in more sophisticated conceptions (such as learning as seeing in a new way). Moreover, the internet-assisted instruction group expressed more orientation toward the approaches of deep motive and deep strategy than the traditional instruction group. However, the students in the internet-assisted instruction group also showed more surface motive than the traditional instruction group did. © 2012 The American Physiological Society.

Chen S.-H.,Graduate Institute of Applied Science and Technology | Chen H.-S.,Graduate Institute of Electro Optical Engineering | Ohta N.,Rochester Institute of Technology | Luo M.R.,University of Leeds
Journal of Imaging Science and Technology | Year: 2013

It is essential to understand preferred skin colors for color reproduction in the display industry. This article presents three psychophysical experiments that were conducted to determine the preferred skin color ranges of East Asian women by East Asian observers on the chromatic and lightness components of CIELAB color space displayed on a standard sRGB-gamut display. In the first experiment, the preferred skin color was searched using various settings of correlated color temperatures (CCTs) and luminance levels on the screen. The results indicate that the most preferred skin color on a display had small differences between various images varying in CCT and luminance level. In the second experiment, a more precise preferred skin color center was produced. The preference scores were analyzed, and the preference map of skin colors was presented on the CIELAB a*b* plane. The final experiment examined the relationship between the lightness of facial skin color and the perceived preference on a display. It was conducted to examine the effect of the lightness component on the preference of facial skin color. It was found that the (C* ab, hab) value of the most preferred skin colors of East Asian women is (25.4, 50.5), with an L * value of 65. © 2013 Society for Imaging Science and Technology.

Jufar S.R.,National Taiwan University of Science and Technology | Huang R.F.,National Taiwan University of Science and Technology | Hsu C.M.,National Taiwan University of Science and Technology | Hsu C.M.,Graduate Institute of Applied Science and Technology
AIAA Journal | Year: 2013

The effects of pulsation intensity on the flow and mixing characteristics of acoustically excited swirling doubleconcentric jets were studied experimentally. The central jet was excited with various pulsation intensities. The flow evolution process, jet spread width, velocity instabilities, and jet dispersion characteristics were examined by the flow visualization, edge-detection technique, hot-wire anemometer, and tracer-gas concentration detection, respectively. As the pulsation intensity was increased over 0.16 one vortex ring was induced during each excitation cycle. This induced vortex ring evolved downstream and suddenly broke up into turbulent eddies at a distance downstream from the jet exit. The dispersion and mixing were simultaneously dominated by two mechanisms: 1) the breakup of the induced vortex ring into turbulent eddies, and 2) the near-field entrainment of the induced vortex rings. The former was more important at pulsation intensities smaller than about 0.5, whereas the latter was more prominent at pulsation intensities larger than approximately 0.5. The results of flow visualization as well as the measurements of velocity, fluctuation intensity, turbulence time and length scales, and tracer-gas-concentration distributions showed close correlations in interpreting the flow and mixing characteristics. Exciting the swirling double-concentric jets at a pulsation intensity of 1.0 might increase the mixing index by 90% over the unexcited jets. Copyright © 2013 by the American Institute of Aeronautics and Astronautics, Inc.

Huang R.F.,National Taiwan University of Science and Technology | Yang H.F.,National Taiwan University of Science and Technology | Hsu C.M.,National Taiwan University of Science and Technology | Hsu C.M.,Graduate Institute of Applied Science and Technology
Journal of Propulsion and Power | Year: 2013

The flame behavior, thermal structure, and combustion product concentrations of the flames of nonpulsating and pulsating plane jets were examined and compared.Anonpulsating plane jet was modified into a pulsating plane jet by introducing the jet fluids through a jet-impingement fluidic oscillator. The flame behavior was analyzed by photographing the flame from the lateral direction and focusing on the near burner region. The flame length was taken from long-exposure photographs. The temperature and combustion product concentrations were measured by using a fine-wire thermocouple and a gas analyzer, respectively. The results showed that the pulsating jet flame is significantly shorter and wider than the nonpulsating jet flame. A difference in the flame length larger than 30% was typical. The central region temperature distributions of the pulsating jet flame presented wide plateaus of high temperatures. The maximum temperature that the pulsating jet flame may attain was higher than that of the nonpulsating jet flame by about 250°C. The pulsating jet flame presented significantly larger CO2 concentration, smaller CO concentration, and smaller unburned C3H8 than those of the nonpulsating jet flame, which implied that the combustion happening in the pulsating jet is more complete than that happening in the nonpulsating jet.

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