Browsing by Author "Cheng, Yu-Hsiang"

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A size-segregation method for monitoring the diurnal characteristics of atmospheric black carbon size distribution at urban traffic sites
(2014-06-01)
Cheng, Yu-Hsiang
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Liao, Chung-Wen
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Liu, Zhen-Shu
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Tsai, Chuen-Jinn
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Hsi, Hsing-Cheng
Understanding the characteristics of the size distribution of ambient black carbon (BC) in distinct environments is critical because the influence of BC aerosols on climate, visibility, and human health depends strongly on the distribution of BC aerosols over the particle size spectrum. In this study, a novel method for determining the mass size distribution of BC in atmospheric aerosols was developed. This size-segregation method relies on measuring BC in parallel using two aethalometers, one of which is used to measure the total BC (BCT) mass concentration as a reference level and the other is used to measure the BC (BC;) mass concentration for BC sizes below specific particle sizes that are selected using a size cut-off inlet. In this study, this method was applied to measure BC in atmospheric samples at an urban traffic site. The aethalometers were operated continually from December 15, 2012 to January 31, 2013, and from February 15, 2013 to March 31, 2013. The measurement results presented in this paper are for the diurnal variation patterns, average concentrations, mass fractions, and size distributions of BC aerosols. The results indicate that BC T mass concentration is approximately 2.8 mu g m(-3) in the Taipei urban area. The levels of BC at this sampling site were affected markedly by traffic emission levels and local wind speed. At the sampling site, the average BC2.5/BCT; BC1.0/BCT, BC0.5/BCT, BC0.25/BCT, and BC0.1/BCT were 0.96 +/- 0.04, +/- 0.92 +/- 0.07, 0.89 +/- 0.04, 0.73 +/- 0.10, and 0.18 +/- 0.08, respectively. The results indicate that approximately 90% of the BC aerosols were smaller than 0.5 mu m, that most of the BC aerosols (55%) were in the size range of 0.1-0.25 mu m, and that approximately 18% of the BC aerosols were ultrafine. Moreover, the daily average mass size distribution of BC exhibited a single accumulation mode at 0.16 gm at this sampling site. The mode of the BC mass size distribution at rush hour (9 AM) was only 0.14 mu m, which is smaller than the daily average. Moreover, the mode of the BC mass size distribution at an early morning hour (3 AM) was 0.18 mu m, and a minor coarse mode was also observed during this period. The results further revealed that the geometric diameter (D-pg) of the BC aerosols varied between 0.14 and 0.22 mu m and the geometric standard deviation (sigma(g)) of these BC aerosols ranged between 1.4 and 2.3 during the sampling period. Because BC exhibits extremely low chemical reactivity; the size distribution of BC in the atmosphere does not change substantially except through coagulation. (c) 2014 Elsevier Ltd. All rights reserved.
Concentrations of ultrafine particles at a highway toll collection booth and exposure implications for toll collectors
(2010-12-15)
Cheng, Yu-Hsiang
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Huang, Cheng-Hsiung
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Huang, Hsiao-Lin
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Tsai, Chuen-Jinn
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環境工程研究所
Research regarding the magnitude of ultrafine particle levels at highway toll stations is limited. This study measured ambient concentrations of ultrafine particles at a highway toll station from October 30 to November 1 and November 5 to November 6, 2008. A scanning mobility particle sizer was used to measure ultrafine particle concentrations at a ticket/cash tollbooth. Levels of hourly average ultrafine particles at the tollbooth were about 3-6 times higher than those in urban backgrounds, indicating that a considerable amount of ultrafine particles are exhausted from passing vehicles. A bi-modal size distribution pattern with a dominant mode at about <6 nm and a minor mode at about 40 nm was observed at the tollbooth. The high amounts of nanoparticles in this study can be attributed to gas-to-particle reactions in fresh fumes emitted directly from vehicles. The influences of traffic volume, wind speed, and relative humidity on ultrafine particle concentrations were also determined. High ambient concentrations of ultrafine particles existed under low wind speed, low relative humidity, and high traffic volume. Although different factors account for high ambient concentrations of ultrafine particles at the tollbooth, measurements indicate that toll collectors who work close to traffic emission sources have a high exposure risk. (C) 2010 Elsevier ay. All rights reserved.
High-efficiency parallel-plate wet scrubber (PPWS) for soluble gas removal
(2015-03-04)
Chien, Chih-Liang
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Tsai, Chuen-Jinn
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Sheu, Shiang-Ru
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Cheng, Yu-Hsiang
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Stank, Alexander Mihailovich
A parallel-plate wet scrubber (PPWS) was designed and tested to control low-concentration soluble acid gases using a multi-parallel-plate module (MPPM) to replace typical tower packings. The parallel plates in the MPPM were made of polypropylene coated with nano-TiO2 particles to enhance hydrophilicity for scrubbing liquid to form uniform liquid film. The gap between the plates was maintained at 3 mm, providing channels through which soluble gas pollutants in the upward gas stream were absorbed by the downward scrubbing liquid film on the surfaces. The removal efficiency was tested using HCl, HNO3, and CH3COOH of 0.02-2 ppmv at different retention times and liquid-to-gas ratios. Results show that when the retention time was 0.1, 0.3 and 0.5 s, the removal efficiency of the present scrubber for HCI, HNO3, and CH3COOH in low concentration was greater than 91%, 95%, and 98%, respectively. The MPPM significantly enhances the removal efficiency of the present scrubber, especially in low inlet concentration range (0.02-1 ppmv), which was greater than 99% for HCl and HNO3 and 98% for CH3COOH at the liquid-to-gas ratio of 18.5 L/m(3), the retention time of 0.5 s, and the pressure drop of 0.2 cm H2O. The experimental removal efficiencies of the MPPM are in good agreement with theoretical predictions. It is expected that the present PPWS can be scaled up as an efficient control device with low pressure drop for low-concentration soluble acid and basic gases. (C) 2015 Elsevier B.V. All rights reserved.
Improving the Localization Accuracy for Sigfox Low-Power Wide Area Networks
(2019-01-01)
Wang, Shie-Yuan
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Cheng, Yu-Hsiang
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Tarng, Jenn-Hwan
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交大名義發表
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資訊工程學系
Sigfox is a new LPWAN (Low-Power Wide Area Networks) wireless technology proposed for IoT applications. Its transmit power is only 22.5 dBm, but its wireless transmission range can be up to 30 km in open space. In this paper, we propose a new machine learning-based localization method to predict the location of a Sigfox module. Our method divides the space around each base station into a few sectors and trains a more accurate path-loss-to-distance model for each sector to reflect its site specific multipath propagation environment. Our experimental results measured in a big city show that the maximum distance errors of our method are much smaller than those of the official Sigfox localization service in many cases.
Long-Term Performance Studies of a LoRaWAN-based PM2.5 Application on Campus
(2018-01-01)
Wang, Shie-Yuan
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Zou, Ji-Jhe
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Chen, Yo-Ru
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Hsu, Chun-Chia
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Cheng, Yu-Hsiang
Recently, LoRa/LoRaWAN has been proposed as a promising LPWAN technology for Internet-of-Things (IoT) applications. For monitoring the long-term PM2.5 air quality on our campus, starting from February 1 2017, we have set up a LoRaWAN-based PM2.5 air quality monitoring system on our campus. In total, twenty-two PM2.5 sensor devices have been operating at the rooftop of buildings or on the lamp poles since then. Each of these PM2.5 sensor devices uses a LoRaWAN module to send its most recent PM2.5 value to the LoRaWAN gateway every 72 seconds. After being received successfully by the LoRaWAN gateway, the packets carrying these values were stored into a database with their SNR/RSSI information. With the sequence numbers added by our PM2.5 application running on each device, the packets stored in the database provide many important information about the long-term packet loss rate performance of LoRaWAN on campus. In this paper, we process these data to report real long-term performance of LoRaWAN when used on campus.
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.
miRTarBase 2020: updates to the experimentally validated microRNA-target interaction database
(2020-01-08)
Huang, Hsi-Yuan
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Lin, Yang-Chi-Dung
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Li, Jing
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Huang, Kai-Yao
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Shrestha, Sirjana
MicroRNAs (miRNAs) are small non-coding RNAs (typically consisting of 18-25 nucleotides) that negatively control expression of target genes at the post-transcriptional level. Owing to the biological significance of miRNAs, miRTarBase was developed to provide comprehensive information on experimentally validated miRNA-target interactions (MTIs). To date, the database has accumulated >13,404 validated MTIs from 11,021 articles from manual curations. In this update, a text-mining system was incorporated to enhance the recognition of MTI-related articles by adopting a scoring system. In addition, a variety of biological databases were integrated to provide information on the regulatory network of miRNAs and its expression in blood. Not only targets of miRNAs but also regulators of miRNAs are provided to users for investigating the up- and downstream regulations of miRNAs. Moreover, the number of MTIs with high-throughput experimental evidence increased remarkably (validated by CLIP-seq technology). In conclusion, these improvements promote the miRTarBase as one of the most comprehensively annotated and experimentally validated miRNA-target interaction databases.
Performance of LoRa-based IoT Applications on Campus
(2017-01-01)
Wang, Shie-Yuan
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Chen, Yo-Ru
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Chen, Tzu-Yang
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Chang, Chia-Hung
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Cheng, Yu-Hsiang
To promote smart campus, National Chiao Tung University is deploying several location-based IoT applications based on wireless communications technologies including LoRa and NB-IoT. The applications are indoor/outdoor environment conditions monitoring (such as PM2.5, temperature, and humidity), emergency buttons, and so on. This paper uses PM2.5 measurement application as an example to present the performance of LoRa when it is used on campus. We investigated the LoRa transmission performance from LoRa end-devices to the LoRa gateway. We show how packet losses were affected by the distance between the end-device and the gateway, the transmit power, the payload length, the antenna angle, the time of day, and the weather conditions. The pattern of LoRa packet losses were also measured and we found that in our long-term PM2.5 monitoring application, more than 99% of LoRa packet losses occurred with three or less consecutive packet losses.