Reinforced concrete beams under drop-weight impact loads

Yi Chen,D. Roger J. Owen,Y. T. Feng,Philip J. Thiele,Ian M. May 한국계산역학회 2006 Computers and Concrete, An International Journal Vol.3 No.2

This paper describes the results of an investigation into high mass-low velocity impact behaviour of reinforced concrete beams. Tests have been conducted on fifteen 2.7 m or 1.5 m span beams under drop-weight loads. A high-speed video camera has been used at rates of up to 4,500 frames per second in order to record the crack formation, propagation, particle spallation and scabbing. In some tests the strain in the reinforcement has been recorded using 밆urham?strain gauged bars, a technique developed by Scott and Marchand (2000) in which the strain gauges are embedded in the bars, so that the strains in the reinforcement can be recorded without affecting the bond between the concrete and the reinforcement. The impact force acting on the beams has been measured using a load cell placed within the impactor. A high-speed data logging system has been used to record the impact load, strains, accelerations, etc., so that time histories can be obtained. This research has led to the development of computational techniques based on combined continuum/discontinuum methods (finite/discrete element methods) to permit the simulation of impact loaded reinforced concrete beams. The implementation has been within the software package ELFEN (2004). Beams, similar to those tested, have been analysed using ELFEN a good agreement has been obtained for both the load-time histories and the crack patterns.

Characterization and Functional Analysis of Bacillus aryabhattai CY for Acrylic Acid Biodegradation: Immobilization and Metabolic Pathway

Yi Chen,Min Zhao,Liyong Hu,Zeyu Wang,Dzmitry Hrynsphan,Jun Chen 한국생물공학회 2021 Biotechnology and Bioprocess Engineering Vol.26 No.6

Acrylic acid has been widely used in various industrial applications but is harmful to human health and the environment. A novel and efficient degrading acrylic acid bacterium was isolated and identified as Bacillus aryabhattai CY. In this study, batch experiments were conducted to evaluate the biodegradation of acrylic acid by B. aryabhattai CY, which were immobilized in calciumalginate beads under different conditions. The components of the alginate beads were optimized by the response surface method, and the degradation performance of the immobilized cells was determined. Relative to the free cells, experiment results showed that the immobilized cells can achieve complete degradation of 100 mg/L acrylic acid in 24 h under the optimal conditions of SA 6% (w/v), CaCl2 1% (w/v), and immobilization time of 6 h. According to Haldane's model, the maximum specific growth rate (μmax) of the free cells and immobilized cells were 0.165/h and 0.210/h, respectively. Experiment data revealed that acrylic acid showed an inhibitory effect on biodegradation by B. aryabhattai CY, especially at concentration higher than 100 mg/L. Furthermore, the reusability of the immobilized cells revealed that the acrylic acid removal rate was above 93.70% within the eight cycles. The immobilized cells also showed higher removal efficiencies in wider ranges of temperature (20°C-60°C) and pH (5.0-10.0) than the free cells. Moreover, the possible degradation intermediates were proposed during the biodegradation of acrylic acid by GC-MS analysis. Results indicated that immobilized beads might have a potential environmental implication in the purification of practical acrylic acid wastewater.

Soft-chemistry Based Fabrication of Gallium Nitride Nanoparticles

Yi Chen,Mohammad Maniruzzaman1,김재환 한국정밀공학회 2011 International Journal of Precision Engineering and Vol.12 No.3

Gallium nitride (GaN) nanoparticles were fabricated with two different fabrication processes based on soft-chemistry methods, and the results were compared. Before fabricating GaN, gallium oxide peroxide (GaO(OH)) nanorods or amorphous gallium oxide (Ga2O3) particles were fabricated. For the first method, the gallium nitride (Ga(NO3)3) was dissolved into the nitric acid and adjusted pH to approximately 7. The solid-sol was converted to Ga2O3 by heating at 400 °C for 4 h. The Ga2O3 was converted to GaN in a tube furnace at 900 °C for 1 h with ammonia flow. The synthesized GaN has spherical crystalline structure. For the second method, Ga(NO3)3 was dissolved in deionized water and adjusted pH to 5 and 7 using potassium hydroxide. Well-defined and uniform diameter (approximately 200 nm) and length (approximately 1000 nm) of GaO(OH) nanorods were fabricated. For the pH 7 case, the length of the nanorods became approximately 500 nm. The nanorods became a spherical shape after conversion. X-ray diffraction patterns of the GaN nanoparticles showed a wurtzite structural characteristic.

Phase Transformation Comparison of TiO2 Nanorods and TiO2 Thin Film After Annealing

Yi Chen,Sang Yeol Yang,김재환 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.3

This paper reports the degree of phase transformation of titanium dioxide (TiO2) thin film and TiO2 nanorods before and after annealing. TiO2 nanorods were synthesized with titanium isoproxide (TIP) in Oleic acid,having approximately 5 nm diameter and 30 nm length. TiO2 thin film was fabricated by sol-gel method using TIP, ethanol and hydrochloric acid. The characteristics of TiO2 nanorods and thin film were investigated with transmission electron microscope, atomic force microscope and x-ray diffraction patterns. Although the TiO2 thin film shows no crystallite peak, as-synthesized TiO2 nanorods show broad anatase phase diffraction peaks. After annealing the TiO2 nanorods at 850°C for 3 h, only approximately 3.1% of crystallite phase was transformed from anatase phase to rutile phase. This slow phase transformation might be due to the small diameter of the nanorods, which is thermodynamically more stable than the anatase crystallite phase. However, although the film has small grains on the surface, approximately 59.5% of phase was transformed from anatase to rutile crystallite structure after the thin film annealing. This large amount of phase transformation might be due to the two dimensional structure of the thin film.

Social Identity at Work : Interpreter’s Grammatical Choices and Interpersonal Alignment

Yi Chen,Zhongwei Song 이화여자대학교 통역번역연구소 2018 T&I review Vol.8 No.-

This study explores the role Chinese government in-house interpreters have played at several high-level annual press conferences hosted by the Chinese government. By analyzing their interpreting choices for elements of MOOD, defined in the Systemic Functional Linguistic as a discourse analysis tool and using data from a self-built corpus consisting of multiple video clips of the events, this study has discovered that the interpreters realise a level of interpersonal alignment with only one party in interpreter-mediated communication, and that the choices of alignment are heavily affected by the interpreter’s evaluation of the power relationship. The findings also suggest that although greatly constrained by their institutional roles, these interpreters remain as linguistic professionals. However, their grammatical choices demonstrate a tendency of their shifting social positions between the speaker and the addressees, betraying their deliberate efforts in embracing two roles in interpreting for the press conferences - one as inseparable part of the institution with allegiance pledged to the government, and the other as individual interpreters adhering to the norms of the profession.

An Effective Method for Deproteinization of Bioactive Polysaccharides Extracted from Lingzhi (Ganoderma atrum)

Yi Chen,Mingyong Xie,Wenjuan Li,Hui Zhang,Shaoping Nie,Yuanxing Wang,Chang Li 한국식품과학회 2012 Food Science and Biotechnology Vol.21 No.1

Deproteinization procedure is a fundamental step for analyzing polysaccharide from natural plants. In this study, in the course of refining bioactive polysaccharides from lingzhi (Ganoderma atrum), an effective deproteinization method using lead acetate solution was established by comparing with other available methods. The percentages of deproteinization, polysaccharide loss, and its antioxidant activities loss were used as the index to evaluate and optimize the precipitation experimental conditions. The results showed that the modified method, precipitation with the addition of 0.4-0.52%(w/v) lead acetate, was superior to the others, as evidenced by the highest deproteinization efficiency (88%), as well as the lowest polysaccharide loss (17%). And notably its antioxidant activity also remained good (loss 15%). It provides a simple prefractionation step for the analysis of polysaccharide from natural plants. Polysaccharide isolated by this method is in the native state. Our method may offer a rapid method for removing protein from plant polysaccharides in large scale.

A Wide Range Conductometric pH Sensor Made With Titanium Dioxide/Multiwall Carbon Nanotube/Cellulose Hybrid Nanocomposite

Yi Chen,Seong Cheol Mun,Jaehwan Kim IEEE 2013 IEEE SENSORS JOURNAL Vol.13 No.11

<P>We report the fabrication and characterization of a pH sensor made with titanium dioxide (TiO<SUB>2</SUB>)/multiwall carbon nanotube (MWCNT)/cellulose hybrid nanocomposite. The TiO<SUB>2</SUB>-coated MWCNTs are synthesized by hydrothermal process. The X-ray diffraction and Raman spectra observations show that high anatase crystalline TiO<SUB>2</SUB> nanoparticles are well formed on the surface of MWCNTs. After blending the TiO<SUB>2</SUB>/MWCNTs with cellulose solution, the TiO/MWCNT/cellulose hybrid nanocomposite is made and used for the pH sensor. This nanocomposite pH sensor exhibits two linear regions in its conductance between pH 1 and 12. Large surface area of the hybrid nanocomposite increases adsorption sites of ions so as to increase the pH sensitivity as well as sensing range. The long-term stability test and reusable test demonstrate that this hybrid nanocomposite pH sensor is useful for many practical applications. The pH sensing mechanism of this hybrid nanocomposite pH sensor is also discussed in this paper.</P>

Giant parathyroid adenoma masquerading as a goiter

( Yichen Ho ),( Ming-chieh Tsai ),( Shuen-han Dai ),( Shih-ping Cheng ) 대한신장학회 2024 Kidney Research and Clinical Practice Vol.43 No.1

Optimize OTDOA-based Positioning Accuracy by Utilizing Multiple Linear Regression Model under NB-IoT Technology

Yichen Pan(판이첸),Jaesoo Kim(김재수) 한국컴퓨터정보학회 2020 한국컴퓨터정보학회 학술발표논문집 Vol.28 No.2

NB-IoT(Narrow Band Internet of Things) is an emerging LPWAN(Low Power Wide Area Network) radio technology. NB-IoT has many advantages like low power, low cost, and high coverage. However low bandwidth and low sampling rates also lead to poor positioning accuracy. This paper proposed a solution to optimize positioning accuracy under the OTDOA(Observed Time Difference of Arrival) approach by utilizing MLR(Multiple Linear Regression) models. Through the MLR model to predict the influence degree of weather(temperature, humidity, light intensity and air pressure) on the arrival time of signal transmission to improve the measurement accuracy. The improvement of measurement accuracy can greatly improve IoT applications based on NB-IoT.

Design and Testing of a Mechanical Power Take-off System for Rolling-type Wave Energy Converter

Yichen Jiang,Yuhao Peng,Yuan Sun,Zhi Zong,Lei Sun 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.5

Salter’s Duck can convert wave energy to mechanical energy with high efficiency up to 90%. The limitations and challenges in the usage of Salter’s Duck for energy production include preventing hydraulic system from the risk of leaking hydraulic oil and removing complex huge fixed bracket. This paper presents the conceptual design and an experimental investigation of a mechanical power-take-off (PTO) system for the floating Salter’s Duck. The PTO system is fully installed inside of the Salter’s Duck. It consists of double counter-rotating flywheels converting the bi-directional rotation of the wave energy converter into a stable unidirectional rotation that drives a rotary generator to produce electricity. The bi-to-unidirectional function is achieved through inertial wheels, thus the novel PTO system is free of large supporting structures and hydraulic cylinders. In this paper, a detailed conceptual PTO design is proposed firstly. Further, the influence of the swing amplitude and rotation period of the wave energy converter on the power extraction efficiency is investigated. Then, the influence of the electrical load on the power-extraction efficiency is researched. In the end, the effect of the speed increasing ratio on the mechanical efficiency is examined. The experimental results show that the new type of generator mechanism can produce electricity stably.