Browsing by Author "Chen, Chih-Yen"

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Confocal displacement sensor with varifocal lens
(2015)
Weng, Chun-Jen
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Lan, Tzu-Hsien
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Hwang, Chi-Hung
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Liu, Da-Ren
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Chen, Chih-Yen
a confocal displacement sensor with a varifocal lens and a multi-wavelength rainbow laser was established in this study. The surface curvature of varifocal lens was varied by different current driving so that the focal length can be easily changed. Thus, we can quickly measure the distance between the sensor head and targets by detecting the reflective power according to the principle of confocal laser. This rainbow laser can operate at four different wavelengths. The laser beams with different colors can be used to measure the dispersion of varifocal lens. The range of measuring displacement with 20X objective lens in this displacement sensor is from 4.9mm to 5.9mm. The FWHM resolution of displacement is about 70 mu m. The step-height aluminate plate was measured by this system and the error of measuring distance is less than 35 mu m (0.75%).
Development of Novel Lightweight Dual-Phase Al-Ti-Cr-Mn-V Medium-Entropy Alloys with High Strength and Ductility
(2020-01-01)
Liao, Yu-Chin
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Chen, Po-Sung
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Li, Chao-Hsiu
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Tsai, Pei-Hua
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Jang, Jason S. C.
A novel lightweight Al-Ti-Cr-Mn-V medium-entropy alloy (MEA) system was developed using a nonequiatiomic approach and alloys were produced through arc melting and drop casting. These alloys comprised a body-centered cubic (BCC) and face-centered cubic (FCC) dual phase with a density of approximately 4.5 g/cm(3). However, the fraction of the BCC phase and morphology of the FCC phase can be controlled by incorporating other elements. The results of compression tests indicated that these Al-Ti-Cr-Mn-V alloys exhibited a prominent compression strength (1940 MPa) and ductility (30%). Moreover, homogenized samples maintained a high compression strength of 1900 MPa and similar ductility (30%). Due to the high specific compressive strength (0.433 GPag/cm(3)) and excellent combination of strength and ductility, the cast lightweight Al-Ti-Cr-Mn-V MEAs are a promising alloy system for application in transportation and energy industries.
Germanium-assisted growth of titanium dioxide nanowires for enhanced photocatalytic and electron emission performance
(2020-11-15)
Chen, Chih-Yen
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Lin, Tzu-Chien
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Chuang, Wen-Shuo
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Chang, Jeng-Kuei
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Lee, Sheng-Wei
In this study, free-standing and well-aligned titanium dioxide (TiO2) nanowires were grown on a Ti foil by precisely controlling the growth temperature and the thickness of the Ge catalyst layer. The catalyst layer played an important role in activating the surface of the Ti foil, facilitating the growth of TiO2 nanowires on it in a chemical vapor deposition furnace system. The structure of the TiO2 nanowires was investigated using scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The photocatalytic experiment results showed that the optimum Ge catalyst layer thickness significantly improved the rhodamine B (RhB) degradation efficiency of the nanowires. The TiO2 nanowires grown using a 40-nm-thick Ge layer could degrade 74% of RhB after 5 h of ultraviolet irradiation. In addition, the TiO2 nanowires exhibited excellent electron field emission performance as compared to the TiO2 nanocrystals grown without the Ge catalyst layer. The results suggested that TiO2 nanowires grown using a Ge catalyst layer are promising materials for next-generation electronic emitters and photocatalytic systems.
In Situ Observation of Dehydration-Induced Phase Transformation from Na2Nb2O6-H2O to NaNbO3
(2012-10-25)
Jung, Jong Hoon
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Chen, Chih-Yen
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Wu, Wen-Wei
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Hong, Jung-Il
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Yun, Byung Kil
We have monitored the phase transformation from a Sandia octahedral molecular sieve Na2Nb2O6-H2O to a piezoelectric NaNbO3 nanowire through in situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements at high temperatures. After dehydration at 288 degrees C, the Na2Nb2O6-H2O becomes significantly destabilized and transforms into NaNbO3 with the increase of time. The phase transformation time is exponentially proportional to the inverse of temperature, for example, similar to 10(5) is at 300 degrees C and similar to 10(1) at 500 degrees C, and follows an Arrhenius equation with the activation energy of 2.0 eV. Real time TEM investigation directly reveals that the phase transformation occurs through a thermally excited atomic rearrangement due to the small difference of Gibbs free energy between two phases. This work may provide a clue of kinetic control for the development of high piezoelectric lead-free alkaline niobates and a deep insight for the crystallization of oxide nanostructures during a hydrothermal process.
Mammalian Ste20-like protein kinase 3 mediates the bioenergetics of mitochondria
(2013-04-01)
Yuan, Chiun-Jye
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Chen, Chih-Yen
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生物科技學系
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Department of Biological Science and Technology
Measuring the thickness of transparent objects using a confocal displacement sensor
(2017-01-01)
Weng, Chun-Jen
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Lu, Bo-Rong
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Cheng, Pi-Ying
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Hwang, Chi-Hung
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Chen, Chih-Yen
this paper reports on a confocal displacement sensor with varifocal lens used to measure the thickness of transparent materials. The focal length of the varifocal lens is adjusted by varying the current. Laser light passing through a transparent target lying within the range of the focal length crosses two interfaces; i.e., first from air to glass and then from glass to air. The signals associated with the interface were of higher intensity than that measure at other points along the z axis. A power meter is used to measure the power and LabVIEW is used to record a power-current graph. The current gap between the two peaks can be translated into values of displacement, indicating the thickness of the material.
Rapid displacement sensor based on fitting scan
(2016)
Ye, Zheng-Jie
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Hwang, Chi-Hung
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Cheng, Pi-Ying
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Chen, Chih-Yen
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Weng, Chun-Jen
A rapid displacement sensor with a varifocal lens based on a method of fitting scan is proposed for 3D surface profiling. The focal length of the varifocal lens can be adjusted by varying the driving current. By detecting the reflective power of the reflected laser, the displacement can be obtained. By integrating a LabVIEW program based on a Levenberg-Marquardt algorithm in this system, the measuring speed can be substantially improved. Finally, the 3D surface profile of a step-height sample was successfully scanned by this displacement sensor.
Real-Time Image-Based Defect Inspection System of Internal Thread for Nut
(2019-08-01)
Lin, Chun-Fu
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Lin, Sheng-Fuu
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Hwang, Chi-Hung
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Tu, Hao-Kai
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Chen, Chih-Yen
The most important components of the internal nut thread inspection process are measuring the pitch and pitch diameter value and comparing these with their respective specifications, as a test nut is considered to be abnormal when its pitch or pitch diameter does not meet specifications. This paper focuses on defects arising when the pitch diameter does not meet its specification. Because conventional contact strategies are not suited to the real-time inspection of internal thread defects, there have been a number of recent attempts to develop noncontact methods for real-time measurement. Some approaches have applied laser triangulation techniques in which reflected light is used to measure the z-axis depth on an object's surface. Although point lasers have been shown to be highly precise in measuring pitch diameter, the optical architecture involved in these approaches is complicated and, as the laser must be scanned in a pointwise manner to derive cross-sectional measurements, the measurement process is too long to be compatible with real-time defect inspection. In this papere, an image-based method employing a line laser projector was used to develop a real-time image-based nut pitch diameter defect inspection system. The proposed method, which improves upon the conventional, widely used template-matching method for rapid defect detection, was shown to be effective through experimental validation.
Real-time Pitch Diameter Measurement of Internal Thread for Nut using Laser Triangulation
(2017-01-01)
Lin, Chun-Fu
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Hwang, Chi-Hung
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Fang, Hong-Ren
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Chen, Chih-Yen
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Sze, Jyh-Rou
In traditional industrial applications, the thread plug gauge is used to check the pitch diameter of the internal thread of a nut. However, the thread plug gauge can only be used to determine whether the nut was manufactured successfully rather than to measure the value of the pitch diameter. In recent years, several studies have employed a reflected light method such as laser triangulation to scan the outline of an object. However, most research studies using laser triangulation have developed measurement algorithms for specific objects because the properties of an object's appearance and the reflective laser from that object differ greatly. Existing algorithms are consequently not suitable for scanning the outline of the internal thread of a nut and measuring its pitch diameter with laser triangulation. In this paper, we propose a novel, real-time algorithm for measuring the pitch diameter of the internal thread of a nut using laser triangulation. First, a specific image preprocessing procedure designed for a reflective laser in the internal thread of a nut is presented. The result of preprocessing critically affects the measurement accuracy of the proposed method. Thereafter, we propose a measurement algorithm designed for the appearance properties of the internal thread of a nut. Our method can operate in real time because the proposed algorithm can measure the pitch diameter of the internal thread of a nut in only a few steps and simple calculations.
Surface profiling of object using varifocal lens with image contrast
(2019-10-01)
Chen, Chih-Yen
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Wang, Lijuan
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Fan, Chen-Liang
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Cheng, Pi-Ying
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Weng, Chun-Jen
The measurement of automated and fast focusing on the improvement of speed and accuracy is an important issue in industrial inspection and biomedical microscopy. In this study, we developed a novel optical imaging system in which varifocal lenses are used to characterize the 3D surface topography of samples. The performance of the proposed system was evaluated using twelve focusing algorithms. Experimental results demonstrate the feasibility and effectiveness of the proposed system in the near real-time construction of multi-focus fusion images with large depth of field from which to derive 3D surface profiles.