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Control mode selection for modal control of long-span arch bridge

Zhengying LI, Zhengliang LI,

《结构与土木工程前沿(英文)》 2009年 第3卷 第4期   页码 401-406 doi: 10.1007/s11709-009-0052-z

摘要: For seismic control of arch bridge, a model reduction of long-span arch bridge was implemented based on modal analysis. As for the critical mode selection, an approach based on the maximum modal displacement was presented. This approach takes into consideration the effect of external seismic excitation and is more reasonable than only considering dynamic bridge characteristics based on a modal contribution ratio. The time domain and frequency domain analysis method were used to verify the simplified model of the Nimu arch bridge in Tibet as an example. The numerical results show that the method of maximal modal displacement better analyze long-span arch bridge when multisupport seismic excitation must be considered. The reduced-order system also is more in line with the performance of the original model.

关键词: selection     reduced-order     excitation     long-span     simplified    

Gold nanoparticles/single-stranded DNA-reduced graphene oxide nanocomposites based electrochemical biosensor

《化学科学与工程前沿(英文)》 2021年 第15卷 第6期   页码 1572-1582 doi: 10.1007/s11705-021-2112-4

摘要: High density and uniform distribution of the gold nanoparticles functionalized single-stranded DNA modified reduced graphene oxide nanocomposites were obtained by non-covalent interaction. The positive gold nanoparticles prepared by phase inversion method exhibited good dimensional homogeneity and dispersibility, which could readily combine with single-stranded DNA modified reduced graphene oxide nanocomposites by electrostatic interactions. The modification of single-stranded DNA endowed the reduced graphene oxide with favorable biocompatibility and provided the preferable surface with negative charge for further assembling of gold nanoparticles to obtain gold nanoparticles/single-stranded DNA modified reduced graphene oxide nanocomposites with better conductivity, larger specific surface area, biocompatibility and electrocatalytic characteristics. The as-prepared nanocomposites were applied as substrates for the construction of cholesterol oxidase modified electrode and well realized the direct electron transfer between the enzyme and electrode. The modified gold nanoparticles could further catalyze the products of cholesterol oxidation catalyzed by cholesterol oxidase, which was beneficial to the enzyme-catalyzed reaction. The as-fabricated bioelectrode exhibited excellent electrocatalytic performance for the cholesterol with a linear range of 7.5‒280.5 μmol·L‒1, a low detection limit of 2.1 μmol·L‒1, good stability and reproducibility. Moreover, the electrochemical biosensor showed good selectivity and acceptable accuracy for the detection of cholesterol in human serum samples.

关键词: reduced graphene oxide     gold nanoparticles     electrochemical biosensor     cholesterol oxidase     cholesterol    

High-order phase-field model with the local and second-order max-entropy approximants

Fatemeh AMIRI

《结构与土木工程前沿(英文)》 2019年 第13卷 第2期   页码 406-416 doi: 10.1007/s11709-018-0475-5

摘要: We approximate the fracture surface energy functional based on phase-field method with smooth local maximum entropy (LME) and second-order maximum entropy (SME) approximants. The higher-order continuity of the meshfree methods such as LME and SME approximants allows to directly solve the fourth-order phase-field equations without splitting the fourth-order differential equation into two second-order differential equations. We will first show that the crack surface functional can be captured more accurately in the fourth-order model with smooth approximants such as LME, SME and B-spline. Furthermore, smaller length scale parameter is needed for the fourth-order model to approximate the energy functional. We also study SME approximants and drive the formulations. The proposed meshfree fourth-order phase-field formulation show more stable results for SME compared to LME meshfree methods.

关键词: second-order maximum entropy     local maximum entropy     second- and fourth-order phase-field models     B-spline    

Superhydrophobic, mechanically flexible and recyclable reduced graphene oxide wrapped sponge for highly

Lijuan Qiu, Ruiyang Zhang, Ying Zhang, Chengjin Li, Qian Zhang, Ying Zhou

《化学科学与工程前沿(英文)》 2018年 第12卷 第3期   页码 390-399 doi: 10.1007/s11705-018-1751-6

摘要:

Water pollution has become an urgent issue for our modern society, and it is highly desirable to rapidly deal with the water pollution without secondary pollution. In this paper, we have prepared a reduced graphene oxide (RGO) wrapped sponge with superhydrophobicity and mechanically flexibility via a facile low-temperature thermal treatment method under a reducing atmosphere. The skeleton of this sponge is completely covered with RGO layers which are closely linked to the skeleton. This sponge has an abundant pore structure, high selectivity, good recyclability, low cost, and outstanding adsorption capacity for floating oil or heavy oil underwater. In addition, this sponge can maintain excellent adsorption performance for various oils and organic solvents over 50 cycles by squeezing, and exhibits extremely high separation efficiencies, up to 6 × 106 and 3.6 × 106 L·m−3·h−1 in non-turbulent and turbulent water/oil systems, respectively. This superhydrophobic adsorbent with attractive properties may find various applications, especially in large-scale removal of organic contaminants and oil spill cleanup.

关键词: superhydrophobicity     mechanically flexibility     water/oil separation     reduced graphene oxide wrapped sponge    

An assemble-to-order production planning with the integration of order scheduling and mixed-model sequencing

Baoxi WANG, Zailin GUAN, Yarong CHEN, Xinyu SHAO, Ming JIN, Chaoyong ZHANG

《机械工程前沿(英文)》 2013年 第8卷 第2期   页码 137-145 doi: 10.1007/s11465-013-0251-0

摘要:

For assemble-to-order enterprises, both order scheduling and mixed-model sequencing need to be taken into consideration in the formulation of order-oriented assembly plan. First, determining production priority for the received orders, and then conducting assembly sequence to the mixed-model products in each order. Order scheduling is aimed to ensure order delivery with the optimization goal of minimal total overdue time, while product sequencing is aimed to minimize the makespan so as to meet the requirement on completion time of the order. In the end, the paper establishes a mixed integer programming model based on an industrial case, and makes programming calculation with Xpress-MP to accomplish an order-oriented assembly plan conforming to actual production.

关键词: mixed-model assembly line     assemble-to-order     order scheduling     sequencing    

Split-order consolidation optimization for online supermarkets: Process analysis and optimization models

《工程管理前沿(英文)》   页码 499-516 doi: 10.1007/s42524-022-0221-5

摘要: The large-scale online supermarket is a newly emerging online retailing mode which brings great convenience to people. Online supermarkets are characterized by having large amounts of daily orders with potentially multiple items, diverse delivery times, and a high order-split rate. Multiple shipments for one order caused by order splitting result in high cost and disturbance and a large number of discarded consumable packages at online retailers and customers, causing severe damage to the environment. Accordingly, research on split-order consolidation fulfilment is critical for the advancement of the practice and theory in the context of highly complex online retailing. This paper first analyzes the characteristics and the challenges associated with the split-order consolidation problem that online supermarket is confronting and summarizes the new operational process of split-order consolidation fulfilment. Then, a time–space network optimization model is built, and its corresponding solution algorithm is presented to solve the questions of where and when to consolidate the split orders. Finally, the computation results of the numerical experiments are provided to verify the effectiveness of the algorithm, and a sensitivity analysis of the relevant parameters is performed. This work highlights the effect of order consolidation processes and fulfilment methods on the order fulfilment decision-making for online supermarkets. The purpose of this article is to help pave the way for more effective online supermarket management and order implementation.

关键词: online supermarkets     split-order consolidation     time–space network     genetic algorithm    

Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption

Junxiong LIN , Lan WANG ,

《环境科学与工程前沿(英文)》 2009年 第3卷 第3期   页码 320-324 doi: 10.1007/s11783-009-0030-7

摘要: The best-fit equations of linear and non-linear forms of the two widely used kinetic models, namely pseudo-first-order and pseudo-second-order equations, were compared in this study. The experimental kinetics of methylene blue adsorption on activated carbon was used for this research. Both the correlation coefficient () and the normalized standard deviation Δ(%) were employed as error analysis methods to determine the best-fitting equations. The results show that the non-linear forms of pseudo-first-order and pseudo-second-order models were more suitable than the linear forms for fitting the experimental data. The experimental kinetics may have been distorted by linearization of the linear kinetic equations, and thus, the non-linear forms of kinetic equations should be primarily used to obtain the adsorption parameters. In addition, the Δ(%) method for error analysis may be better to determine the best-fitting model in this case.

关键词: adsorption     pseudo-first order     pseudo-second order     kinetic model     linear method     non-linear method    

Multi-effect anthraquinone-based polyimide enclosed SnO/reduced graphene oxide composite as high-performance

《化学科学与工程前沿(英文)》 2023年 第17卷 第9期   页码 1231-1243 doi: 10.1007/s11705-023-2306-z

摘要: The cycling stability of SnO2 anode as lithium-ion battery is poor due to volume expansion. Polyimide coatings can effectively confine the expansion of SnO2. However, linear polyimides are easily dissolved in ester electrolytes and their carbonyls is not fully utilized during charging/discharging process. Herein, the SnO2 enclosed with anthraquinone-based polyimide/reduced graphene oxide composite was prepared by self-assembly. Carbonyls from the anthraquinone unit provide fully available active sites to react with Li+, improving the utilization of carbonyl in the polyimide. More exposed carbonyl active sites promote the conversion of Sn to SnO2 with electrode gradual activation, leading to an increase in reversible capacity during the charge/discharge cycle. In addition, the introduction of reduced graphene oxide cannot only improve the stability of polyimide in the electrolyte, but also build fast ion and electron transport channels for composite electrodes. Due to the multiple effects of anthraquinone-based polyimide and the synergistic effect of reducing graphene oxide, the composite anode exhibits a maximum reversible capacity of 1266 mAh·g−1 at 0.25 A·g−1, and maintains an excellent specific capacity of 983 mAh·g−1 after 200 cycles. This work provides a new strategy for the synergistic modification of SnO2.

关键词: anthraquinone-based polyimide     multi-effect     tin dioxide     reduced graphene oxide     lithium-ion battery    

Synthesis of hydrophobic carbon nanotubes/reduced graphene oxide composite films by flash light irradiation

Kai Wang, Jinbo Pang, Liwei Li, Shengzhe Zhou, Yuhao Li, Tiezhu Zhang

《化学科学与工程前沿(英文)》 2018年 第12卷 第3期   页码 376-382 doi: 10.1007/s11705-018-1705-z

摘要:

Carbon nanotubes/graphene composites have superior mechanical, electrical and electrochemistry properties with carbon nanotubes as a hydrophobicity boosting agent. Their extraordinary hydrophobic performance is highly suitable for electrode applications in lithium ion batteries and supercapacitors which often employ organic electrolytes. Also the hydrophobic features enable the oil enrichment for the crude oil separation from seawater. The ever reported synthesis routes towards such a composite either involve complicated multi-step reactions, e.g., chemical vapor depositions, or lead to insufficient extrusion of carbon nanotubes in the chemical reductions of graphene oxide, e.g., fully embedding between the compact graphene oxide sheets. As a consequence, the formation of standalone carbon nanotubes over graphene sheets remains of high interests. Herein we use the facile flash light irradiation method to induce the reduction of graphene oxides in the presence of carbon nanotubes. Photographs, micrographs, X-ray diffraction, infrared spectroscopy and thermogravimetric analysis all indicate that graphene oxides has been reduced. And the contact angle tests confirm the excellent hydrophobic performances of the synthesized carbon nanotube/reduced graphene oxide composite films. This one-step treatment represents a straightforward and high efficiency way for the reduction of carbon nanotubes/graphene oxides composites.

关键词: carbon nanotubes     graphene composite     flash irradiation method     reduced graphene oxide     contact angles    

Higher-order mode effects on the seismic performance of tall piers

Zhongguo GUAN, Jianzhong LI, Yan XU, Hao LU

《结构与土木工程前沿(英文)》 2011年 第5卷 第4期   页码 496-502 doi: 10.1007/s11709-011-0131-9

摘要: A comprehensive analysis was conducted to investigate the seismic performance of a typical tall bridge pier through incremental dynamical analysis (IDA). The effect of higher-order modes was studied specifically. The results showed that higher-order modes significantly contributed to the structural seismic response and should not be neglected. Including these modes resulted in an additional hinge midway up the pier. No plastic hinge would occur at this location for conventional bridge piers. Higher-order modes also led to an out-of-phase response between the hinge rotation at the pier bottom and the displacement at the top. This means that the displacement-based seismic design method cannot correctly predict the mechanical state of the critical hinge and therefore is not suitable for use in the seismic design of tall piers. Mistakenly using the displacement-based seismic design method for tall piers may result in a seriously unsafe condition.

关键词: tall bridges     higher-order mode effects     incremental dynamic analysis    

Fischer-Tropsch synthesis by reduced graphene oxide nanosheets supported cobalt catalysts: Role of support

Hasan Oliaei Torshizi, Ali Nakhaei Pour, Ali Mohammadi, Yahya Zamani, Seyed Mehdi Kamali Shahri

《化学科学与工程前沿(英文)》 2021年 第15卷 第2期   页码 299-309 doi: 10.1007/s11705-020-1925-x

摘要: In this paper, a series of cobalt catalysts supported on reduced graphene oxide (rGO) nanosheets with the loading of 5, 15 and 30 wt-% were provided by the impregnation method. The activity of the prepared catalysts is evaluated in the Fischer-Tropsch synthesis (FTS). The prepared catalysts were carefully characterized by nitrogen adsorption-desorption, hydrogen chemisorption, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, temperature programmed reduction, transmission electron microscopy, and field emission scanning electron microscopy techniques to confirm that cobalt particles were greatly dispersed on the rGO nanosheets. The results showed that with increasing the cobalt loading on the rGO support, the carbon defects are increased and as a consequence, the reduction of cobalt is decreased. The FTS activity results showed that the cobalt-time yield and turnover frequency passed from a maximum for catalyst with the Co average particle size of 15 nm due to the synergetic effect of cobalt reducibility and particle size. The products selectivity results indicated that the methane selectivity decreases, whereas the C selectivity raises with the increasing of the cobalt particle size, which can be explained by chain propagation in the primary chain growth reactions.

关键词: cobalt catalyst     cobalt particle size     Fischer-Tropsch synthesis     reduced graphene oxide     supported catalyst    

Numerical simulation of sudden-expansion two-phase flows with two-scale second-order moment particle

ZENG Zhuoxiong, HAN Shoulei, ZHOU Lixing

《能源前沿(英文)》 2007年 第1卷 第2期   页码 202-206 doi: 10.1007/s11708-007-0026-6

摘要: A two-scale second-order moment particle turbulence model is developed, based on the concept of particle large-scale fluctuation due to turbulence and particle small-scale fluctuation due to collision. The model is employed to simulate gas-particle flows in a sudden-expansion chamber. Simulation results are compared with the experimental results and with those obtained by the single-scale second-order moment two-phase turbulence model. It is shown that the two-scale model is with higher calculating accuracy than the single-scale model.

关键词: gas-particle     single-scale second-order     large-scale fluctuation     second-order     sudden-expansion    

strong>Fabrication and photocatalytic ability of an Au/TiO2/reduced

Fenghe Lv, Hua Wang, Zhangliang Li, Qi Zhang, Xuan Liu, Yan Su

《环境科学与工程前沿(英文)》 2018年 第12卷 第1期 doi: 10.1007/s11783-017-0977-8

摘要: A new type of Au/TiO /reduced graphene oxide (RGO) nanocomposite was fabricated by the hydrothermal synthesis of TiO on graphene oxide followed by the photodeposition of Au nanoparticles. Transmission electron microscopy images showed that Au nanoparticles were loaded onto the surface of both TiO and RGO. Au/TiO /RGO had a better photocatalytic activity than Au/TiO for the degradation of phenol. Electrochemical measurements indicated that Au/TiO /RGO had an improved charge transfer capability. Meanwhile, chemiluminescent analysis and electron spin resonance spectroscopy revealed that Au/TiO /RGO displayed high production of hydrogen peroxide and hydroxyl radicals in the photocatalytic process. This high photocatalytic performance was achieved via the addition of RGO in Au/TiO /RGO, where RGO served not only as a catalyst support to provide more sites for the deposition of Au nanoparticles but also as a collector to accept electrons from TiO to effectively reduce photogenerated charge recombination.

关键词: Reduced graphene oxide     Au     TiO2     Nanocomposite     Photocatalysis    

Inhibition of bromate formation by reduced graphene oxide supported cerium dioxide during ozonation of

Bei Ye, Zhuo Chen, Xinzheng Li, Jianan Liu, Qianyuan Wu, Cheng Yang, Hongying Hu, Ronghe Wang

《环境科学与工程前沿(英文)》 2019年 第13卷 第6期 doi: 10.1007/s11783-019-1170-z

摘要: GO or RGO promotes bromate formation during ozonation of bromide-containing water. CeO2/RGO significantly inhibits bromate formation compared to RGO during ozonation. CeO2/RGO shows an enhancement on DEET degradation efficiency during ozonation. Ozone (O3) is widely used in drinking water disinfection and wastewater treatment. However, when applied to bromide-containing water, ozone induces the formation of bromate, which is carcinogenic. Our previous study found that graphene oxide (GO) can enhance the degradation efficiency of micropollutants during ozonation. However, in this study, GO was found to promote bromate formation during ozonation of bromide-containing waters, with bromate yields from the O3/GO process more than twice those obtained using ozone alone. The promoted bromate formation was attributed to increased hydroxyl radical production, as confirmed by the significant reduction (almost 75%) in bromate yield after adding t-butanol (TBA). Cerium oxide (less than 5 mg/L) supported on reduced GO (xCeO2/RGO) significantly inhibited bromate formation during ozonation compared with reduced GO alone, and the optimal Ce atomic percentage (x) was determined to be 0.36%, achieving an inhibition rate of approximately 73%. Fourier transform infrared (FT-IR) spectra indicated the transformation of GO into RGO after hydrothermal treatment, and transmission electron microscope (TEM) results showed that CeO2 nanoparticles were well dispersed on the RGO surface. The X-ray photoelectron spectroscopy (XPS) spectra results demonstrated that the Ce3+/Ce4+ ratio in xCeO2/RGO was almost 3‒4 times higher than that in pure CeO2, which might be attributed to the charge transfer effect from GO to CeO2. Furthermore, Ce3+ on the xCeO2/RGO surface could quench Br⋅ and BrO⋅ to further inhibit bromate formation. Meanwhile, 0.36CeO2/RGO could also enhance the degradation efficiency of N,N-diethyl-m-toluamide (DEET) in synthetic and reclaimed water during ozonation.

关键词: Bromate     Catalytic ozonation     Graphene oxide     Cerium dioxide    

Tacholess order-tracking approach for wind turbine gearbox fault detection

Yi WANG, Yong XIE, Guanghua XU, Sicong ZHANG, Chenggang HOU

《机械工程前沿(英文)》 2017年 第12卷 第3期   页码 427-439 doi: 10.1007/s11465-017-0452-z

摘要:

Monitoring of wind turbines under variable-speed operating conditions has become an important issue in recent years. The gearbox of a wind turbine is the most important transmission unit; it generally exhibits complex vibration signatures due to random variations in operating conditions. Spectral analysis is one of the main approaches in vibration signal processing. However, spectral analysis is based on a stationary assumption and thus inapplicable to the fault diagnosis of wind turbines under variable-speed operating conditions. This constraint limits the application of spectral analysis to wind turbine diagnosis in industrial applications. Although order-tracking methods have been proposed for wind turbine fault detection in recent years, current methods are only applicable to cases in which the instantaneous shaft phase is available. For wind turbines with limited structural spaces, collecting phase signals with tachometers or encoders is difficult. In this study, a tacholess order-tracking method for wind turbines is proposed to overcome the limitations of traditional techniques. The proposed method extracts the instantaneous phase from the vibration signal, resamples the signal at equiangular increments, and calculates the order spectrum for wind turbine fault identification. The effectiveness of the proposed method is experimentally validated with the vibration signals of wind turbines.

关键词: wind turbine     variable-speed operating conditions     Vold-Kalman filtering     tacholess order tracking    

标题 作者 时间 类型 操作

Control mode selection for modal control of long-span arch bridge

Zhengying LI, Zhengliang LI,

期刊论文

Gold nanoparticles/single-stranded DNA-reduced graphene oxide nanocomposites based electrochemical biosensor

期刊论文

High-order phase-field model with the local and second-order max-entropy approximants

Fatemeh AMIRI

期刊论文

Superhydrophobic, mechanically flexible and recyclable reduced graphene oxide wrapped sponge for highly

Lijuan Qiu, Ruiyang Zhang, Ying Zhang, Chengjin Li, Qian Zhang, Ying Zhou

期刊论文

An assemble-to-order production planning with the integration of order scheduling and mixed-model sequencing

Baoxi WANG, Zailin GUAN, Yarong CHEN, Xinyu SHAO, Ming JIN, Chaoyong ZHANG

期刊论文

Split-order consolidation optimization for online supermarkets: Process analysis and optimization models

期刊论文

Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption

Junxiong LIN , Lan WANG ,

期刊论文

Multi-effect anthraquinone-based polyimide enclosed SnO/reduced graphene oxide composite as high-performance

期刊论文

Synthesis of hydrophobic carbon nanotubes/reduced graphene oxide composite films by flash light irradiation

Kai Wang, Jinbo Pang, Liwei Li, Shengzhe Zhou, Yuhao Li, Tiezhu Zhang

期刊论文

Higher-order mode effects on the seismic performance of tall piers

Zhongguo GUAN, Jianzhong LI, Yan XU, Hao LU

期刊论文

Fischer-Tropsch synthesis by reduced graphene oxide nanosheets supported cobalt catalysts: Role of support

Hasan Oliaei Torshizi, Ali Nakhaei Pour, Ali Mohammadi, Yahya Zamani, Seyed Mehdi Kamali Shahri

期刊论文

Numerical simulation of sudden-expansion two-phase flows with two-scale second-order moment particle

ZENG Zhuoxiong, HAN Shoulei, ZHOU Lixing

期刊论文

strong>Fabrication and photocatalytic ability of an Au/TiO2/reduced

Fenghe Lv, Hua Wang, Zhangliang Li, Qi Zhang, Xuan Liu, Yan Su

期刊论文

Inhibition of bromate formation by reduced graphene oxide supported cerium dioxide during ozonation of

Bei Ye, Zhuo Chen, Xinzheng Li, Jianan Liu, Qianyuan Wu, Cheng Yang, Hongying Hu, Ronghe Wang

期刊论文

Tacholess order-tracking approach for wind turbine gearbox fault detection

Yi WANG, Yong XIE, Guanghua XU, Sicong ZHANG, Chenggang HOU

期刊论文