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Xianghao Zheng,Suqi Zhang,Yuning Zhang,Jinwei Li,Yuning Zhang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.12
Evaluation of the operational stability of the main shaft is of great significance to ensure the security and reliability of the prototype reversible pump turbine (RPT). In the present paper, the experimental study was carried out using the sensors with high accuracy to obtain the shaft displacement signals under different load conditions of the RPT in the generating mode. A set of signal extraction procedure based on ensemble empirical mode decomposition, permutation entropy (PE) and modified wavelet soft-threshold de-noising method is proposed to reduce the influences of the random noises and extract the effective components within the signal. The PE values of the extracted shaft displacement signals are all below 0.3, illustrating that good extraction results have been achieved. Meanwhile, the typical shape evolution of the extracted shaft orbit with load variations at the turbine guide bearing is also depicted in detail. And the PE analysis result of the extracted shaft orbit can effectively reflect the evolution of different internal flow patterns under different load partitions of the RPT, which are 0.33-0.36 for low partial load partition, 0.22-0.30 for medium load partition and 0.30-0.32 for high partial load partition, respectively.
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Dependence assessment in human reliability analysis under uncertain and dynamic situations
Xianghao Gao,Xiaoyan Su,Hong Qian,Xiaolei Pan 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.3
Since reliability and security of man-machine system increasingly depend on reliability of human, humanreliability analysis (HRA) has attracted a lot of attention in many fields especially in nuclear engineering. Dependence assessment among human tasks is a important part in HRA which contributes to anappropriate evaluation result. Most of methods in HRA are based on experts’ opinions which are subjectiveand uncertain. Also, the dependence influencing factors are usually considered to be constant,which is unrealistic. In this paper, a new model based on DempstereShafer evidence theory (DSET) andfuzzy number is proposed to handle the dependence between two tasks in HRA under uncertain anddynamic situations. First, the dependence influencing factors are identified and the judgments on thefactors are represented as basic belief assignments (BBAs). Second, the BBAs of the factors that varyingwith time are reconstructed based on the correction BBA derived from time value. Then, BBAs of allfactors are combined to gain the fused BBA. Finally, conditional human error probability (CHEP) isderived based on the fused BBA. The proposed method can deal with uncertainties in the judgments anddynamics of the dependence influencing factors. A case study is illustrated to show the effectiveness andthe flexibility of the proposed method.
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김인수,Xianghao Ren,장진수,Jin Wook Lee,유혜원,김성조,Jung Sun Heo,Am Jang,한호재 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.2
N,N-diethyl-m-toluamide (DEET) is an insect repellent used worldwide, and a common micropollutant in aquatic environments. However, few studies have addressed the molecular mechanism of DEET toxicity and its effects on cell growth and apoptosis. The purpose of this study was to investigate the effect of DEET on the expression of the cell cycle and apoptosis regulatory proteins in human BE(2)-M17 cells. The results showed that DEET significantly decreased the cell viability (40.6 ~ 68.9% of control)at concentrations of 500 ~ 4,000 mg/L. Also, DEET significantly decreased the expressions of CDK 2, CDK 4, and cyclin D1 (3.9 ~ 86.6% of control), at concentrations of 50~ 400 mg/L but from 100 mg/L for cyclin E. Furthermore,DEET significantly increased the expression of caspase-3(223.1 ~ 1,770.6% of control), but significantly decreased Bcl-2 expression (46.1 ~ 86.3% of control) at all concentrations tested. In conclusion, DEET partially affected the expression of CDK/cyclin molecules, but fully affected the expressions of caspase-3 and Bcl-2 in BE(2)-M17 cells.
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Optimal sensor placement for structural health monitoring based on deep reinforcement learning
Yong Huang,Xianghao Meng,Haoyu Zhang,Kailiang Jia,Hui Li 국제구조공학회 2023 Smart Structures and Systems, An International Jou Vol.31 No.3
In structural health monitoring of large-scale structures, optimal sensor placement plays an important role because of the high cost of sensors and their supporting instruments, as well as the burden of data transmission and storage. In this study, a vibration sensor placement algorithm based on deep reinforcement learning (DRL) is proposed, which can effectively solve non-convex, high-dimensional, and discrete combinatorial sensor placement optimization problems. An objective function is constructed to estimate the quality of a specific vibration sensor placement scheme according to the modal assurance criterion (MAC). Using this objective function, a DRL-based algorithm is presented to determine the optimal vibration sensor placement scheme. Subsequently, we transform the sensor optimal placement process into a Markov decision process and employ a DRLbased optimization algorithm to maximize the objective function for optimal sensor placement. To illustrate the applicability of the proposed method, two examples are presented: a 10-story braced frame and a sea-crossing bridge model. A comparison study is also performed with a genetic algorithm and particle swarm algorithm. The proposed DRL-based algorithm can effectively solve the discrete combinatorial optimization problem for vibration sensor placements and can produce superior performance compared with the other two existing methods.
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Chae, Kyu-Jung,Ren, Xianghao ELSEVIER 2016 APPLIED ENERGY -BARKING THEN OXFORD- Vol.179 No.-
<P>Among many options to improve energy self-sufficiency in sewage treatment plants, heat extraction using a heat pump holds great promise, since wastewater contains considerable amounts of thermal energy. The actual heat energy demand at municipal wastewater treatment plants (WWTPs) varies widely with time; however, the heat pumps typically installed in WWTPs are of the on/off controlled fixed-speed type, thus mostly run intermittently at severe part-load conditions with poor efficiency. To solve this mismatch, a specially designed, fixed-inverter hybrid heat pump system incorporating a fixed-speed compressor and an inverter-driven, variable-speed compressor was developed and tested in a real WWTP. In this hybrid configuration, to improve load response and energy efficiency, the base-heat load was covered by the fixed-speed compressor consuming relatively less energy than the variable-speed type at nominal power, and the remaining varying load was handled by the inverter compressor which exhibits a high load-match function while consuming relatively greater energy. The heat pump system developed reliably extracted heat from the treated effluent as a heat source for heating and cooling purposes throughout the year, and actively responded to the load changes with a high measured coefficient of performance (COP) of 4.06 for heating and 3.64 for cooling. Moreover, this hybrid operation yielded a performance up to 15.04% better on part loads than the single inverter operation, suggesting its effectiveness for improving annual energy saving when applied to highly load-fluctuating real WWTPs. To improve the overall efficiency of the heat recovery system, although the heat pump is the largest energy-consuming component, taking up 56.0-68.5% of the total energy, new efforts to develop a novel design are also needed to make the heat exchanger more energy-efficient. (C) 2016 Elsevier Ltd. All rights reserved.</P>
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Zhang, Yuzhi,Kong, Xianghao,Zhu, Xiaoping,Wang, Runlian,Yan, Yichai,Jia, Zhihai Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.5
Twenty-four cannulated Small-tailed Han${\times}$Poll Dorset wethers (BW $47.5{\pm}2.1kg$) were used to determine the effects of forage to concentrate ratio (40:60 vs. 70:30), monensin supplementation (0, 15 or 30 ppm, DM basis) and interactions of these two factors on cis-9, trans-11 conjugated linoleic acid (cis-9, trans-11 CLA) and trans-11 octadecenoic acid (trans11-$C_{18:1}$) concentrations in ruminal contents and plasma in sheep. The experiment was designed as a $2{\times}3$ factorial. The diet contained Chinese wild rye grass hay (Aneurolepidium Chinese), cracked corn, soybean meal, NaCl, limestone and trace mineral premix. Dietary crude fat and linoleic acid ($C_{18:2n-6}$) were adjusted with soybean oil to about 7.0% and 24.0 mg/g (DM basis), respectively. High forage diets increased (p<0.001) the concentrations of trans11-$C_{18:1}$ and cis-9, trans-11 CLA in ruminal contents and plasma. Monensin supplementation increased (p<0.001) the concentration of trans11-$C_{18:1}$ in ruminal contents, but had no effect on that of cis-9, trans-11 CLA. Concentrations of trans11-$C_{18:1}$ (p<0.019) and cis-9, trans-11 CLA (p<0.022) in plasma increased with dietary monensin levels. Interactions of forage: concentrate ratio and monensin level tended to affect the concentrations of trans11-$C_{18:1}$ (p<0.091) and $C_{18:2n-6}$ (p<0.083) in ruminal contents. Increasing forage levels increased the concentrations of trans11-$C_{18:1}$ and cis-9, trans-11 CLA in the rumen. Supplementing with monensin increased the ruminal production of trans11-$C_{18:1}$ and concentrations of trans11-$C_{18:1}$ and cis-9, trans-11 CLA in plasma.
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Skin Deiodinase Profiles after Melatonin Manipulated in Chinese Inner Mongolia Cashmere Goats
Yue, Chunwang,Du, Lixin,Zhu, Xiaoping,Kong, Xianghao,Zhang, Wei,Jia, Zhihai Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.10
The roles of melatonin in the control of deiodinase (MD) activity in cashmere goat skin and associated cashmere fibre growth were investigated. Eighteen half-sib Chinese Inner Mongolia cashmere wethers were allocated randomly to two groups (n = 9/group). One group was implanted subcutaneously with melatonin (2 mg/kg BW) at three 2-monthly intervals while the other group served as a control. All goats were maintained under natural photoperiodic conditions and were grazed on natural pasture. The plasma melatonin concentration showed a significant difference (p<0.01) between the implant group (M) and the control group (C) but plasma $T_4$ (or $T_3$) showed no significant difference (p>0.05). The monodeiodinase type II (MDII) activity in skin tended to increase gradually from the summer solstice to November. During July and August, the activity of MDII for the M group was higher (p<0.05) than that of the C group; also during this period, there was a significant positive correlation between MDII activity of skin and cashmere fibre growth rate. The monodeiodinase type III (MDIII) activity and the ratio of MDIII and MDII tended to decrease from the summer solstice to November. The ratio of MDIII and MDII for the M group was lower (p<0.05) than that of the C group in July and August. The cashmere fibre growth rate of the M group was significantly greater than that of the C group in July (p<0.01), August (p<0.001) and September (p<0.05). The cashmere fibre diameter and guard hair and body weight were not influenced (p>0.05) by melatonin implantation. The results demonstrate that melatonin plays an important role in the regulation of skin MD activity. Simultaneously, the cashmere fibre elongation stimulated by melatonin may result from enhanced MDII activity during a period of two months after melatonin treatment.
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Chae, Kyu-Jung,Kim, In-Soo,Ren, Xianghao,Cheon, Kyeong-Ho Elsevier 2015 Energy Conversion and Management Vol.101 No.-
<P><B>Abstract</B></P> <P>A micro-hydropower (MHP) system with a flow-variable turbine was tested for over one year to investigate its applicability for small-scale municipal wastewater treatment plants (WWTP) with severe flow fluctuations. The applied MHP was designed as a semi-Kaplan, equipped with only adjustable turbine blades without guide vanes, hence it is simple in its mechanical structure and is inexpensive while providing high-level performance. To exploit as much hydro-energy as possible, a maximum water level tracking control scheme in the forebay tank was employed and the turbine blade angle was accurately adjusted corresponding to the oncoming flow rate, which allows water to hit the blade in the best direction for maximum efficiency. Despite its micro-scale (12.3kW at design conditions of 4.30m net head and 0.35m<SUP>3</SUP>/s flow rate), the applied MHP can work stably over a wide range of flows from 57% to 123% of the rated design flow, with the highest turbine efficiency of 91.3% and its corresponding overall electric efficiency of 80.3%. Even as the flow rate decreases to 23% of the design flow, the turbine still runs but at relatively lower efficiencies. Because of wide flow adjustability, the tested MHP can generate power even at extreme flow rates so that an almost complete amount (95.8%) of WWTP’s total effluent was used to produce 68.1MWh annually. In addition, as compared with similar WWTP-based hydropower systems in South Korea, the tested MHP achieved 1.78–2.80 times higher normalized electricity in both flow rate and net head, indicating a more efficient use of the flow and head. These results should draw new interest in the WWTP-based MHP, which was considered unfeasible in the past in Korea due to its low efficiency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Micro-hydropower (MHP) with a flow-variable turbine was investigated. </LI> <LI> Simple semi-Kaplan with only adjustable turbine blades showed reliable performances. </LI> <LI> Maximum water level tracking control scheme in the forebay tank was employed. </LI> <LI> Despite the micro-scale, the applied MHP can work stably over a wide range of flows. </LI> <LI> MHP is an effective option for achieving energy self-sufficient sewage treatment plants. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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