One-step solvothermal synthesis of poly(arylene ether nitrile) decorated magnetic composite for methylene blue adsorption from aqueous solution

Zhou Xuefei,Miao Wei,Cheng Wenxi,Lin Haowei,Lin Haowei,Zheng Hongjuan,Cheng Qiaohuan,Wang Renjie,Yao Chenxue,Liu Xiaobo 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.6

A series of poly(arylene ether nitrile) containing versatile carboxyl and sulfonic groups (CSPEN) were magnetically functionalized by ferroferric oxide (Fe3O4), and the obtained magnetic adsorbents (Fe3O4/CSPEN) were used to remove methylene blue (MB) dye from aqueous solution. The systematical characterizations that including scanning electron microscope (SEM), X-ray powder diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), Fourier transform infrared (FTIR) certified that the Fe3O4/CSPEN possessed versatile functional groups and magnetic separation properties. The batch adsorption studies revealed that the Fe3O4/CSPEN not only displayed high selective adsorption ability for cationic MB in the presence of anionic MO, but also exhibited a removal efficiency as high as 98.2%. Besides, the adsorption kinetics and isotherm matched well with pseudo-second-order model and Langmuir model, respectively, and the maximum adsorption capacity of Fe3O4/CSPEN for MB was 92.029 mg/g. The FTIR and Brunauer-Emmett-Teller (BET) analyses confirmed that the outstanding adsorption capacity of Fe3O4/CSPEN was attributed to their own microporous structure and the electrostatic interaction with MB. Therefore, the modified magnetic adsorbent can be used to selectively remove cationic dye from aqueous solution.

Extreme value modeling of structural load effects with non-identical distribution using clustering

Junyong Zhou,Xin Ruan,Xuefei Shi,Chudong Pan 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.1

The common practice to predict the characteristic structural load effects (LEs) in long reference periods is to employ the extreme value theory (EVT) for building limit distributions. However, most applications ignore that LEs are driven by multiple loading events and thus do not have the identical distribution, a prerequisite for EVT. In this study, we propose the composite extreme value modeling approach using clustering to (a) cluster initial blended samples into finite identical distributed subsamples using the finite mixture model, expectation-maximization algorithm, and the Akaike information criterion; (b) combine limit distributions of subsamples into a composite prediction equation using the generalized Pareto distribution based on a joint threshold. The proposed approach was validated both through numerical examples with known solutions and engineering applications of bridge traffic LEs on a long-span bridge. The results indicate that a joint threshold largely benefits the composite extreme value modeling, many appropriate tail approaching models can be used, and the equation form is simply the sum of the weighted models. In numerical examples, the proposed approach using clustering generated accurate extrema prediction of any reference period compared with the known solutions, whereas the common practice of employing EVT without clustering on the mixture data showed large deviations. Real-world bridge traffic LEs are driven by multi-events and present multipeak distributions, and the proposed approach is more capable of capturing the tendency of tailed LEs than the conventional approach. The proposed approach is expected to have wide applications to general problems such as samples that are driven by multiple events and that do not have the identical distribution.

Traffic control technologies without interruption for component replacement of long-span bridges using microsimulation and site-specific data

Junyong Zhou,Xuefei Shi,Liwen Zhang,Zuo Sun 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.70 No.2

The replacement of damaged components is an important task for long-span bridges. Conventional strategy for component replacement is to close the bridge to traffic, so that the influence of the surrounding environment is reduced to a minimum extent. However, complete traffic interruption would bring substantial economic losses and negative social influence nowadays. This paper investigates traffic control technologies without interruption for component replacement of long-span bridges. A numerical procedure of traffic control technologies is proposed incorporating traffic microsimulation and site-specific data, which is then implemented through a case study of cable replacement of a long-span cable-stayed bridge. Results indicate traffic load effects on the bridge are lower than the design values under current low daily traffic volume, and therefore cable replacement could be conducted without traffic control. However, considering a possible medium or high level of daily traffic volume, traffic load effects of girder bending moment and cable force nearest to the replaced cable become larger than the design level. This indicates a potential risk of failure, and traffic control should be implemented. Parametric studies show that speed control does not decrease but increase the load effects, and flow control using lane closure is not effectual. However, weight control and gap control are very effective to mitigate traffic load effects, and it is recommended to employ a weight control with gross vehicle weight no more than 65 t or/and a gap control with minimum vehicle gap no less than 40 m for the cable replacement of the case bridge.

Seismic Analysis and Evaluation of Y-shaped EBF with an Innovative SSL-SSBC

Shujun Hu,Sizhi Zeng,Jingang Xiong,Xuefei Wang,Qiang Zhou,Xiong Xinfu 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.3

During severe earthquakes, the ductility and energy dissipation capacity of shear links in Y-shaped eccentrically braced frames (EBFs) are crucial to achieve desirable seismic performance and structural safety. In this study, an innovative SSLSSBC combining the advantages of a shear slotted bolted connection (SSBC) and a very short shear link is developed to improve the seismic performance of Y-shaped EBFs. Finite element (FE) analysis methods are fi rst validated through comparison with existing experimental results for slotted bolted connection and very short shear links. Further, FE simulations of the SSBC, very short shear link with shear slotted bolted connection (SSL-SSBC), and Y-shaped EBF are conducted to determine their mechanical behavior systematically. The FE results demonstrate that a reasonable SSBC can eff ectively increase the ductility and energy dissipation capacity through friction slipping, allowing the SSBC to maintain elastic behavior throughout the entire range of seismic loading, while the very short shear link in the SSL-SSBC could undergo severe damage to dissipate seismic energy. As expected, the SSL-SSBC is capable of working as both a shear dissipation damper and a metallic ductile damper in the Y-shaped EBF. This study also clearly identifi es that no yielding or damage of the very short shear links occurs during small and medium earthquakes, and the deformation and damage of the very short shear link can be minimized during severe earthquakes, allowing the seismic resilience capacity of the Y-shaped EBF to be dramatically enhanced.

Optimization for Scenedesmus obliquus Cultivation: the Effects of Temperature, Light Intensity and pH on Growth and Biochemical Composition

Zhang, Yonggang,Ren, Li,Chu, Huaqiang,Zhou, Xuefei,Yao, Tianming,Zhang, Yalei The Korean Society for Microbiology and Biotechnol 2019 한국미생물·생명공학회지 Vol.47 No.4

Microalgae have been explored as potential host species for biofuel production. Environmental factors affect algal growth and cellular composition. The effects of several key environmental factors, such as temperature, light, and pH of the medium on the growth and biochemical composition of Scenedesmus obliquus were investigated in this study. The highest growth rate of microalgae was observed at an optimal temperature of 25℃, 150 μmol/(m²·s) light intensity, and pH 10.0. The biochemical composition analysis revealed that the carbohydrate content decreased at lower (20℃) or higher temperature (35℃), whereas the protein and lipid contents increase at these temperatures. The fluctuation of light intensity significantly affected the contents of protein, carbohydrate, and lipid. The protein levels varied greatly when the pH of the medium was below 7.0. The carbohydrate and lipid contents significantly increased at pH above 7.0.

High Efficiency Onboard Charger Based on Two-Stage Circuit

Xue Fei,Ma Xin,Li Hongqiang,Zhang Di,Xu Hengshan,Zhou Lei,Wang Chao 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.4

On-board charger (OBC) is key part of electric vehicles. Limited to space and weight, design objectives of OBC are high power-density and high effi ciency. Two-stage circuit is commonly used for 3.3 kW OBC, interleaved power factor correction (ILPFC) is utilized for power factor correction and DC bus voltage regulation, LLC resonant converter is utilized for voltage and power regulations. In this paper, the relationships between the internal parameters and effi ciency of ILPFC are studied by discrete iterative method, and the internal parameters are optimized to improve ILPFC`s effi ciency. Meanwhile, the relationships between the resonant parameters and effi ciency of LLC converter are also studied by fundamental harmonic approximation method to optimize the effi ciency in wide charging voltage. A 3.3 kW OBC prototype is developed to verify the eff ectiveness and correctness of the optimal method, the power factor and total harmonic distortion at full-load state are about 99.99% and 2.98% with the charging voltage ranging from 230 to 430 V, respectively