Browsing by Author "Wu, Cheng-Han"

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A Load-Balanced Guiding Navigation Protocol in Wireless Sensor Networks
(2008)
Chen, Wen-Tsuen
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Chen, Po-Yu
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Wu, Cheng-Han
;
Huang, Chi-Fu
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資訊工程學系
One of the major applications of wireless sensor networks is guiding navigation service with its goal to assist moving objects in leaving a hazardous region safely and quickly. In this paper, we propose a distributed guiding navigation protocol that can guide moving objects to multiple exits with load balancing among multiple navigation paths to the exits. With the assistances of sensor nodes, moving objects are guided to different navigation paths so that they can move to exits as soon as possible without causing congestion. In some traditional navigation algorithms, a sensor may select a wrong guiding direction when an information-updating packet has not flooded through the whole network. Hence, the guiding direction of the sensor may oscillate in a short time and guided objects will confuse with this phenomenon, called direction oscillation problem. This problem will be eliminated in our proposed protocol. Simulation results indicate that our protocol can guide moving objects to exits in shorter time and solve the direction oscillation problem effectively.
Growth and characterization of high quality CIGS films using novel precursors stacked and surface sulfurization process
(2018-07-01)
Wu, Cheng-Han
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Wu, Pu-Wei
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Hsiao, Ruey-Chang
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Hsu, Chun-Yao
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材料科學與工程學系
This study produces high quality Cu(In,Ga)Se-2 (CIGS) solar cells using a two-step process. Stacked In (200 nm)/CuGa (150 similar to 300 nm)/In (500 nm) layers are deposited onto Mo bilayer soda-lime glass by sputtering, using CuGa and In targets, followed by vapor stacking of the elemental Se layers. To produce the CIGS film, the CuGa film is coated in thicknesses of 150, 200, 250 and 300 nm. An appropriate atomic ratio [Cu/(In + Ga), CGI and Ga/(In + Ga), GGI] for the precursors and the CIGS absorption layers composition is easily obtained. Compared to those for the as-deposited precursors, after selenization, the CGI and GGI ratios for CIGS films are almost constant. All CIGS thin films exhibit a peak in the Raman curves at around 173-174 cm(-1), which is identified as the CIGS phase. Following sulfurization, the main peaks for CIGS thin films at (112), (220)/(204) and (312)/(116) indicated that the crystalline quaility were improved. The main peaks for the CIGSS films are slightly greater for (112), (220)/(204) and (312)/(116). The band gap energy is increased from 1.19 eV (for the as-grown) to 1.34 eV (for the absorber layer that is sulfurized at 500 A degrees C for 10 min). The performance of the CIGS absorber films is improved by using a proper holding time for sulfurization.
Measurements of ultrafine particle concentrations and size distribution in an iron foundry
(2008-10-01)
Cheng, Yu-Hsiang
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Chao, Yen-Chi
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Wu, Cheng-Han
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Tsai, Chuen-Jinn
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Uang, Shi-Nian
The number and surface area concentration of ultrafine particles in an iron foundry is of interest as freshly generated ultrafine particles are produced by metal melting, pouring and molding processes. This study measured the number and surface area concentrations of ultrafine particles and their size distributions in an iron foundry using a scanning mobility particle sizer (SMPS). The 10-100 nm ultafine particle number concentrations (NC0.01-0.1) and surface area concentrations (SC0.01-0.1) measured at the iron foundry were 2.07 x 10(4) to 2.82 x 10(5) particles cm(-3) and 67.56 to 2.13 x 10(3) mu m(2) cm(-3), respectively. The concentrations changed dramatically depending on on-site manufacturing conditions. The NC0.01-0.1 levels in the iron foundry were approximately 4.5 times higher on average compared with those in the outdoor ambient environment. These measurement results indicate that the presence of extra particles in the workplace air is within the ultrafine range. Additionally, the analytical results suggest that the number mode diameter can be used to estimate the SC0.01-0.1 levels using the NC0.01-0.1 levels. Moreover. the ultrafine particle number mode diameter was found to be about 46.1 nm in the iron foundry. (C) 2008 Elsevier B.V. All rights reserved.
Particle loss in a critical orifice
(2007-09-01)
Chen, Sheng-Chieh
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Tsai, Chuen-Jinn
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Wu, Cheng-Han
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Pui, David Y. . H.
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Onischuk, Andrei A.
Particle deposition in different regions of a critical orifice assembly was studied numerically and experimentally. The investigated orifice is an O'Keefe E-9 (O'Keefe Control Co.) orifice whose diameter is 0.231 mm and critical flow rate is 0.455 slpm. The orifice assembly has an inlet tube (inner diameter = 10.4 mm, length = 90 mm) and outlet tube (inner diameter = 6.2 mm, length = 60 mm). In the numerical study, axisymmetric, laminar flow field of the orifice assembly was obtained first by solving the Navier-Stokes equations. The diffusion loss of nanoparticles was then calculated by solving the convection-diffusion equation. Inertial impaction and interception loss of 2-10 mu m particles was calculated by tracing particle trajectories in the flow field. In the experimental study, monodisperse NaCl (20-800 nm in aerodynamic diameter) and fluorescein-containing oleic acid (2-10 mu m in aerodynamic diameter) particles were used to test particle loss in both diffusion- and inertial impaction-dominated regimes. The numerical results were compared with the experimental data and good agreement was obtained with the maximum deviation smaller than 10.4%. (C) 2007 Elsevier Ltd. All rights reserved.
Surface active flexible palladium nano-thin-film electrode development for biosensing
(2019-09-01)
Chang, Chia-Yu
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Huang, Yun-Tzu
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Chang, Pang-Chia
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Su, Chien-Hao
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Hsu, Kuo-Chen
Metal atoms on surface edges or with specific coordinates possess high surface potentials, and serve as core atoms for organic molecule bonding. However, these active metal atoms may lose their activity by self-diffusion on the surface. A polyethylene terephthalate (PET) substrate provided a stable rough surface in nanoscale for metal atoms absorption and formation of a stable and active nano-thin-film (NTF) surface. However, the NTF surface roughness decreased with increasing thickness of palladium (Pd) granules, indicating that the surface growth of the Pd film followed a Stranski-Krastanov-like growth model. Therefore, the proper thickness of Pd-NTF on PET substrate (Pd NTF-PET) was developed for electrochemical impedance spectroscopy (EIS). Protein was immobilized on the Pd NTF-PET electrodes within 15 min and its biosensing sensitivity was as low as 0.1 ng per-test in 1 mu l. We expect that the developed Pd NTF-PET electrode can be used for other biosensing applications as well.
VCSEL with bi-layer oxidized aperture enables 140-Gbit/s OFDM Transmission over 100-m-long OM5 MMF
(2019-01-01)
Wu, Wei-Li
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Huang, Cheng-Yi
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Wang, Huai-Yung
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Lin, Yu-Hong
;
Wu, Cheng-Han
A few-mode 850-nm VCSEL chip directly modulated by 16-QAM OFDM data at 140 Gbit/s is demonstrated to enable error-free transmission over 100-m-long OM5 MMF with 3.1-dB power penalty compared to the back-to-back case.