Time filter

Source Type

Taipei, Taiwan

National Taiwan Normal University , or Shīdà 師大, is an institution of higher education and normal school operating out of three campuses in Taipei, Taiwan. NTNU is widely recognized as one of Taiwan's elite higher education institutions. The university enrolls approximately 11,000 students each year. The ratio of undergraduate to graduate students is 6:4. Approximately 1,500 students are international. Wikipedia.

Tsai J.-H.,National Taiwan Normal University
IEEE Transactions on Microwave Theory and Techniques | Year: 2011

In this paper, low-voltage evolution and high-speed operation mixer design are presented for millimeter-wave (MMW) CMOS in-phase/quadrature (I/Q) modulator and demodulator. The modified Gilbert-cell mixer architecture, which eliminates the three-level transistors stacking in the conventional Gilbert-cell mixer, can operate at a reduced supply voltage while maintaining reasonable performance. In addition, IF transimpedance amplifier buffer and wideband RF design are introduced to increase the operation speed of the mixer for MMW gigabit wireless transmission link applications. Using a 0.13-μm CMOS process, the I/Q modulator and demodulator formed with the modified Gilbert-cell mixers are demonstrated at the MMW. Under 1.2-V standard supply voltage, the modulator and demodulator exhibit excellent conversion gain (CG) flatness of -3.5 ± 1.5 dB and -3 ± 1.5 dB from 41 to 69.5 GHz and 31 to 69 GHz, respectively. For 60-GHz wireless personal area network applications, π/4 differential quadrature phase-shift keying, 16 quadrature amplitude modulation, and binary phase-shift keying modulation signal tests are successfully performed through the direct-conversion system. The results show that the presented monolithic microwave integrated circuits can operate at low-voltage and low-power while providing good CG and high data rate, even up to multigigabit. © 2011 IEEE.

Teng T.-P.,National Taiwan Normal University
Energy Conversion and Management | Year: 2013

This study uses thermal conductivity and differential scanning calorimeter experiments to explore the thermal conductivity and phase-change properties of alumina (Al2O3)-water nanofluid produced using a two-step synthesis method. Deionized water (DW) is used as a control group, and the Al2O3-water nanofluid uses chitosan as a dispersant. Nanoparticle morphology and materials were confirmed using transmission electron microscopy (TEM) and X-ray diffraction (XRD), respectively. The results show that adding Al2O3 nanoparticles to DW improves DW thermal conductivity, but adding chitosan reduces the thermal conductivity of Al 2O3-water nanofluid. Adding the nanoparticles to DW affects the phase-change peak temperature and phase change heat. The optimal combination is 0.1 wt.% chitosan and 0.5 wt.% Al2O3 nanoparticles; the charging phase-change peak temperature and latent heat are 53.4% and 97.8% of those in DW, respectively. © 2012 Elsevier Ltd. All rights reserved.

Chen S.-S.,National Taiwan Normal University
IEEE Transactions on Neural Networks | Year: 2011

In this paper, we have three goals: the first is to delineate the advantages of a variably delayed system, the second is to find a more intuitive Lyapunov function for a delayed neural network, and the third is to design a delayed neural network for a quadratic cost function. For delayed neural networks, most researchers construct a Lyapunov function based on the linear matrix inequality (LMI) approach. However, that approach is not intuitive. We provide a alternative candidate Lyapunov function for a delayed neural network. On the other hand, if we are first given a quadratic cost function, we can construct a delayed neural network by suitably dividing the second-order term into two parts: a self-feedback connection weight and a delayed connection weight. To demonstrate the advantage of a variably delayed neural network, we propose a transiently chaotic neural network with variable delay and show numerically that the model should possess a better searching ability than Chen-Aihara's model, Wang's model, and Zhao's model. We discuss both the chaotic and the convergent phases. During the chaotic phase, we simply present bifurcation diagrams for a single neuron with a constant delay and with a variable delay. We show that the variably delayed model possesses the stochastic property and chaotic wandering. During the convergent phase, we not only provide a novel Lyapunov function for neural networks with a delay (the Lyapunov function is independent of the LMI approach) but also establish a correlation between the Lyapunov function for a delayed neural network and an objective function for the traveling salesman problem. © 2011 IEEE.

Shellnutt J.G.,National Taiwan Normal University
Journal of Geophysical Research E: Planets | Year: 2013

The presence of highly evolved igneous rocks on Venus is a controversial issue. The formations of highland terranes and pancake domes are the two principal tectonic and volcanic features which argue in favor of the presence of silicic igneous rocks; however, the lack of water on Venus casts doubt on whether or not granites and rhyolites can form. Data returned to Earth from the Venera 13 and 14 landers show that the surface of Venus is composed of basaltic rocks similar in composition to those found on Earth. Here it is shown that anhydrous and hydrous fractional crystallization modeling using the Venera 13 and 14 data as starting materials can produce compositions similar to terrestrial phonolites and rhyolites. It is suggested that at shallow crustal levels (i.e., ≤ 0.1 GPa), mafic magmas can differentiate into silicic magmas resembling phonolites or rhyolites which may or may not erupt. Furthermore, the hydrous equilibrium partial melting models can produce rocks similar to terrestrial andesites and rhyolites, whereas anhydrous models suggest that there may be a uniquely Venusian type of silicic rock. The silicic rocks, if present, could act as "continental nucleation" sites and/or their presence may facilitate preferential sites of shearing and deformation of the Venusian crust. Key Points Dry fractionation of Venusian basaltic rocks can produce silicic magmasPancake domes may be surficial expression of shallow level magma chambersConcentration of silicic rocks may form continental nucleation sites on Venus ©2013. American Geophysical Union. All Rights Reserved.

Wu C.-R.,National Taiwan Normal University
Progress in Oceanography | Year: 2013

To investigate the interannual variability in the northwestern Pacific, an empirical mode decomposition (EMD) was applied to 17-year Absolute Dynamic Topography (ADT) data west of Luzon Island, the Philippines. The mean sea surface height in this area is an appropriate index for the Kuroshio intrusion into the South China Sea (SCS). Significant interannual fluctuations were extracted by the EMD. The interannual variability was strongly correlated with the Pacific Decadal Oscillation (PDO) index, but not the El Niño-Southern Oscillation (ENSO). This indicated the potential impact of the PDO on the circulation in the area. In the warm phase of the PDO (positive index), a southerly anomalous wind off the Philippines causes a northward shift of the North Equatorial Current Bifurcation Latitude (NECBL). This leads to a weakened Kuroshio off Luzon, favoring Kuroshio intrusion into the SCS. The northward migration of the NECBL also results in a weakened Kuroshio off southeast Taiwan and a larger Kuroshio transport off northeast Taiwan. The abundant westward propagating eddies impinging on the Kuroshio in the Subtropical Countercurrent region increases this transport. Although the ENSO has little effect on monsoonal winds during the warm PDO phase, it has a strong impact on the monsoon and meridional migration of the NECBL during the cold phase of the PDO. Therefore, NECBL variations only show a close correspondence with the ENSO during the cold PDO phase. Because the influence of the ENSO is not stationary, the impact of the PDO should be taken into account when examining interannual variability in the low-latitude western North Pacific. © 2012 Elsevier Ltd.

Discover hidden collaborations