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CFD simulation on membrane distillation of NaCl solution

Zhaoguang XU, Yanqiu PAN, Yalan YU

《化学科学与工程前沿（英文）》 2009年 第3卷 第3期   页码 293-297 doi: 10.1007/s11705-009-0204-7

摘要： A computational fluid dynamics (CFD) simulation that coupled an established heat and mass transfer model was carried out for the air-gap membrane distillation (AGMD) of NaCl solution to predict mass and heat behaviors of the process. The effects of temperature and flowrate on fluxes were first simulated and compared with available experimental data to verify the approach. The profiles of temperature, temperature polarization factor, and mass flux adjacent to the tubular carbon membrane surface were then examined under different feed Reynolds number in the computational domain. Results show that the temperature polarization phenomena can be reduced, and mass flux can be enhanced with increase in the feed Reynolds number.

关键词： membrane distillation     computational fluid dynamics (CFD) simulation     temperature polarization     carbon membrane    

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Computational fluid dynamics applied to high temperature hydrogen separation membranes

Guozhao JI, Guoxiong WANG, Kamel HOOMAN, Suresh BHATIA, Jo?o C. DINIZ da COSTA

《化学科学与工程前沿（英文）》 2012年 第6卷 第1期   页码 3-12 doi: 10.1007/s11705-011-1161-5

摘要： This work reviews the development of computational fluid dynamics (CFD) modeling for hydrogen separation, with a focus on high temperature membranes to address industrial requirements in terms of membrane systems as contactors, or in membrane reactor arrangements. CFD modeling of membranes attracts interesting challenges as the membrane provides a discontinuity of flow, and therefore cannot be solved by the Navier-Stokes equations. To address this problem, the concept of source has been introduced to understand gas flows on both sides or domains (feed and permeate) of the membrane. This is an important solution, as the gas flow and concentrations in the permeate domain are intrinsically affected by the gas flow and concentrations in the feed domain and vice-versa. In turn, the source term will depend on the membrane used, as different membrane materials comply with different transport mechanisms, in addition to varying gas selectivity and fluxes. This work also addresses concentration polarization, a common effect in membrane systems, though its significance is dependent upon the performance of the membrane coupled with the operating conditions. Finally, CFD modeling is shifting from simplified single gas simulation to industrial gas mixtures, when the mathematical treatment becomes more complex.

关键词： membrane     gas separation     computational fluid dynamics     concentration polarization     hydrogen    

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Spin polarization strategy to deploy proton resource over atomic-level metal sites for highly selective

《化学科学与工程前沿（英文）》 2022年 第16卷 第12期   页码 1772-1781 doi: 10.1007/s11705-022-2197-4

摘要： Unlocking of the extremely inert C=O bond during electrochemical CO2 reduction demands subtle regulation on a key “resource”, protons, necessary for intermediate conversion but also readily trapped in water splitting, which is still challenging for developing efficient single-atom catalysts limited by their structural simplicity usually incompetent to handle this task. Incorporation of extra functional units should be viable. Herein, a proton deployment strategy is demonstrated via “atomic and nanostructured iron (A/N-Fe) pairs”, comprising atomically dispersed iron active centers spin-polarized by nanostructured iron carbide ferromagnets, to boost the critical protonation steps. The as-designed catalyst displays a broad window (300 mV) for CO selectivity > 90% (98% maximum), even outperforming numerous cutting-edge M–N–C systems. The well-placed control of proton dynamics by A/N-Fe can promote *COOH/*CO formation and simultaneously suppress H2 evolution, benefiting from the magnetic-proximity-induced exchange splitting (spin polarization) that properly adjusts energy levels of the Fe sites’ d-shells, and further those of the adsorbed intermediates’ antibonding molecular orbitals.

关键词： CO2 electrolysis     single-atom catalysts     spin polarization     proton dynamics     in situ IR spectroscopy     kinetic isotope effect    

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Stress induced polarization switching and coupled hysteretic dynamics in ferroelectric materials

Linxiang WANG, Roderick MELNIK, Fuzai LV

《机械工程前沿（英文）》 2011年 第6卷 第3期   页码 287-291 doi: 10.1007/s11465-011-0230-2

摘要：

The dynamic responses of ferroelectric materials upon external mechanical and electrical stimulations are inherently nonlinear and coupled. In the current paper, a macroscopic differential model is constructed for the coupled hysteretic dynamics via modeling the orientation switching induced in the materials. A non-convex potential energy is constructed with both mechanic and electric field contributions. The governing equations are formulated as nonlinear ordinary differential equations by employing the Euler-Lagrange equation, and can be easily recast into a state space form. Hysteresis loops associated with stress induced polarization switching and butterfly-shaped behavior in ferroelectric materials are also successfully captured. The effects of mechanical loadings on the electrically induced switching are numerically investigated, as well as the mechanically-induced switching with various bias electric fields.

关键词： differential model     state space     electromechanical switching     butterfly effects     hysteresis    

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Dynamic modulation performance of ferroelectric liquid crystal polarization rotators and Mueller matrix

Song ZHANG, Lelun WANG, Anze YI, Honggang GU, Xiuguo CHEN, Hao JIANG, Shiyuan LIU

《机械工程前沿（英文）》 2020年 第15卷 第2期   页码 256-264 doi: 10.1007/s11465-019-0573-7

摘要： A ferroelectric liquid crystal polarization rotator (FLCPR) has been widely used in polarization measurement due to its fast and stable modulation characteristics. The accurate characterization of the modulation performance of FLCPR directly affects the measurement accuracy of the instrument based on liquid crystal modulation. In this study, FLCPR is accurately characterized using a self-developed high-speed Stokes polarimeter. Strong linear and weak circular birefringence are observed during modulation processes, and all the optical parameters of FLCPR are dependent on driving voltage. A dual FLCPR-based Mueller matrix polarimeter is designed on the basis of the Stokes polarimeter. The designed polarimeter combines the advantages of the high modulation frequency of FLCPR and the ultrahigh temporal resolution of the fast polarization measurement system in the Stokes polarimeter. The optimal configuration of the designed polarizer is predicted in accordance with singular value decomposition. A simulated thickness measurement of a 24 nm standard SiO thin film is performed using the optimal configuration. Results show that the relative error in thickness measurement caused by using the unsatisfactory modulation characteristics of FLCPR reaches up to −4.34%. This finding demonstrates the importance of the accurate characterization of FLCPR in developing a Mueller matrix polarizer.

关键词： ferroelectric liquid crystal polarization rotator (FLCPR)     dual liquid crystal Mueller matrix polarizer     design and optimization    

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Kinetics of enhanced adsorption by polarization for organic pollutants on activated carbon fiber

HAN Yanhe, QUAN Xie, ZHAO Huimin, CHEN Shuo, ZHAO Yazhi

《环境科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 83-88 doi: 10.1007/s11783-007-0016-2

摘要： The adsorption kinetics for model pollutants on activated carbon fiber (ACF) by polarization was investigated in this work. Kinetics data obtained for the adsorption of these model pollutants at open-circuit, 400 mV, and -400 mV polarization were applied to the Lagergren equation, and adsorption rate constants () were determined. With the anodic polarization of 400 mV, the capacity of sodium phenoxide was increased from 0.0083 mmol/g at open-circuit to 0.18 mmol/g, and a 17-fold enhancement was achieved; however, the capacity of -nitrophenol was decreased from 2.93 mmol/g at open-circuit to 2.65 mmol/g. With the cathodal polarization of -400 mV, the capacity of aniline was improved from 3.60 mmol/g at open-circuit to 3.88 mmol/g; however, the capacity of sodium dodecylbenzene sulfonate was reduced from 2.20 mmol/g at open-circuit to 1.59 mmol/g. The enhancement for electrosorption changed with dif ferent groups substituting. Anodic polarization enhances the adsorption of benzene with the electron-donating group. But whether anodic or not, cathodal polarization had less effect on the adsorption of electron-accepting aromatic compounds, and decreased the adsorption capacity of benzene-bearing donor-conjugate bridge-acceptor, while increasing its adsorption rate. Electrostatic interaction played a very important role in the electrosorption of ion-pollutants.

关键词： ACF     activated     17-fold enhancement     donor-conjugate bridge-acceptor     Electrostatic interaction    

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Spontaneous polarization enhanced bismuth ferrate photoelectrode: fabrication and boosted photoelectrochemical

《能源前沿（英文）》 2021年 第15卷 第3期   页码 781-790 doi: 10.1007/s11708-021-0782-8

摘要： In this paper, the fabrication of a highly orientated Bi2Fe4O9 (BFO) photoelectrode in the presence of two-dimensional (2D) graphene oxide (GO) was reported. It was found that the GO can be used as a template for controlling the growth of BFO, and the nanoplate composites of BFO/reduced graphene oxide (RGO) with a high orientation can be fabricated. The thickness of the nanoplates became thinner as the ratio of GO increased. As a result, the ferroelectric spontaneous polarization unit arranges itself in the space in a periodic manner, leading to the formation of a polarization field along a special direction. Therefore, the created built-in electric field of the nanoplate composites of BFO/RGO is improved upon the increase of the amount of RGO. As expected, carrier separation is enhanced by the built-in electric field, therefore substantially enhancing the photoelectrochemical (PEC) activity of water splitting compared to pure BFO under the irradiation of visible-light.

关键词： bismuth ferrate     ferroelectric polarisation     photoelectrochemical (PEC) water splitting     graphene oxide (GO)     high orientation    

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极限工程——产品开发和制造中的极化

Andrew Kusiak

《工程（英文）》 2021年 第7卷 第3期   页码 282-284 doi: 10.1016/j.eng.2020.01.012

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偏振模色散对高速光码的影响

饶敏,孙小菡,张明德

《中国工程科学》 2002年 第4卷 第11期   页码 67-70

摘要：

研究一阶、二阶偏振模色散（PMD）对10 Gb/s和40 Gb/s的光传输系统性能的影响，考虑PMD的统计特性，基于基本偏振态（PSP）理论数值模拟了非归零码（NRZ）和归零码（RZ）在传输过程中产生的脉冲畸变以及系统Q值的变化。结果表明，传输速率越高PMD对系统性能的影响越显著，二阶PMD也将不可忽略。另外，RZ码传输性能明显优于NRZ码并且可通过预啁啾进行改善。

关键词： 偏振模色散（PMD）     非归零码（NRZ）     归零码（RZ）     频率啁啾    

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卫星通信大型双极化中国版图赋形微带反射阵天线的优化设计 Research Articles

Gang ZHAO, Yong-chang JIAO, Guan-tao CHEN

《信息与电子工程前沿（英文）》 2020年 第21卷 第1期   页码 159-173 doi: 10.1631/FITEE.1900496

摘要： 设计了一款具有中国版图赋形的大型双频双极化微带反射阵天线。为充分补偿两个频段范围内的空间相位延迟差，采用一种适用于大型双极化反射阵的3层矩形贴片单元。由于赋形区域形状复杂、赋形增益要求很高，该反射阵天线单元数量超过25 000个，优化变量数超过150 000个，导致其设计非常困难。本文首先通过离散快速傅里叶变换及其逆变换建立口径场和远场的一一对应关系，为赋形反射阵天线的优化奠定基础。进而采用基于交替投影的交集方法，优化获得多个典型频率下所有单元的目标反射相位。为避免优化过程陷入局部极值点，采用一种产生合适初始解的新方法。为验证设计方法的有效性，制作了一个7569单元的双极化反射阵天线并进行实验测试。测试与仿真结果吻合良好。为使宽带工作的大型反射阵天线带宽范围的空间相位延迟极小化，提出一种确定馈源最佳位置的方法。为在两个相互正交方向上同时找到单元的最优尺寸，建立一种新的优化模型，通过正多面体优化方法进行优化计算。最后，设计了一款覆盖中国陆地版图的单元数为25 305的双频双极化微带反射阵天线。仿真结果表明，该反射阵天线在两个工作频带范围内均可满足中国版图覆盖要求，证明所提出的复杂赋形波束大型反射阵天线优化设计方法可靠和有效。

关键词： 反射阵；双极化；赋形波束；限相位综合    

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Long-term effects of electrochemical realkalization on carbonated concrete

Peng ZHU, Ji ZHANG, Wenjun QU

《结构与土木工程前沿（英文）》 2020年 第14卷 第1期   页码 127-137 doi: 10.1007/s11709-019-0583-x

摘要： The long-term effects of electrochemical realkalization on carbonated reinforced concrete with a / ratio of 0.65 were studied. Fourteen out of 16 carbonated specimens had been subjected to realkalization seven years ago, and the alkalinity of the concrete, the electrochemical characters (corrosion current density and potential) of the specimens and the corrosion conditions of the steel bars were examined. Results of different specimens and also at different time (4, 10, 13 months and 7 years after realkalization) were compared. According to the phenolphthalein and pH meter test, the alkalinity of the concrete had disappeared after seven years. Based on the potentiodynamic polarization test, various corrosion conditions had developed on the steel bars, which was verified by visual observation. All bars were in the depassivated state, and their corrosion current densities increased significantly after seven years. Cracks developed in some of the specimens, and the diverse compactness of concrete and excessive current of realkalization were considered to be possible causes. The effects of the realkalization treatment vanished after seven years.

关键词： realkalization     concrete     carbonation     polarization curve     corrosion    

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Tracing the impact of stack configuration on interface resistances in reverse electrodialysis by in situ electrochemical impedance spectroscopy

《环境科学与工程前沿（英文）》 2022年 第16卷 第4期 doi: 10.1007/s11783-021-1480-9

摘要：

• RED performance and stack resistance were studied by EIS and LSV.

关键词： Reverse electrodialysis     Electrochemical impedance spectroscopy     Concentration polarization     Spacer shadow effect    

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A Miniature Meta-Optical System for Reconfigurable Wide-Angle Imaging and Polarization-Spectral Detection

Fei Zhang,Minghao Liao,Mingbo Pu,Yinghui Guo,Lianwei Chen,Xiong Li,Qiong He,Tongtong Kang,Xiaoliang Ma,Yuan Ke,Xiangang Luo,

《工程（英文）》 doi: 10.1016/j.eng.2023.07.008

摘要： Wide-angle imaging and spectral detection play vital roles in tasks such as target tracking, object classification, and anti-camouflage. However, limited by their intrinsically different architectures, as determined by frequency dispersion requirements, their simultaneous implementation in a shared-aperture system is difficult. Here, we propose a novel concept to realize reconfigurable dual-mode detection based on electrical-control tunable metasurfaces. As a proof-of-concept demonstration, the simultaneous implementation of wide-angle imaging and polarization-spectral detection in a miniature shared-aperture meta-optical system is realized for the first time via the electrical control of cascaded catenary-like metasurfaces. The proposed system supports the imaging (spectral) resolution of approximately 27.8 line-pairs per millimeter (lp·mm−1; ∼80 nm) for an imaging (spectral) mode from 8 to 14 μm. This system also bears a large field of view of about 70°, enabling multi-target recognition in both modes. This work may promote the miniaturization of multifunctional optical systems, including spectrometers and polarization imagers, and illustrates the potential industrial applications of meta-optics in biomedicine, security, space exploration, and more.

关键词： Metasurfaces     Reconfigurable     Imaging     Spectral    

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Preparation and influence of performance of anodic catalysts for direct methanol fuel cell

WANG Zhenbo, YIN Geping, SHI Pengfei

《化学科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 20-25 doi: 10.1007/s11705-007-0005-9

摘要： This research aims at increasing the utilization of platinum-ruthenium alloy (Pt-Ru) catalysts and thus lowering the catalyst loading in anodes for methanol electrooxidation. The direct methanol fuel cell s (DMFC) anodic catalysts, Pt-Ru/C, were prepared by chemical reduction with a reducing agent added in two kinds of solutions under different circumstances. The reducing agent was added in hot solution with the protection of inert gases or just air, and in cold solution with inert gases. The catalysts were treated at different temperatures. Their performance was tested by cyclic voltammetry and potentiostatic polarization by utilizing their inherent powder microelectrode in 0.5 mol/L CHOH and 0.5 mol/L HSO solution. The structures and micro-surface images of the catalysts were determined and observed by X-ray diffraction and transmission electron microscopy, respectively. The catalyst prepared in inert gases showed a better catalytic performance for methanol electrooxidation than that prepared in air. It resulted in a more homogeneous distribution of the Pt-Ru alloy in carbon. Its size is small, only about 4.5 nm. The catalytic performance is affected by the order of the reducing agent added. The performance of the catalyst prepared by adding the reductant at constant temperature of the solution is better than that prepared by adding it in the solution at 0?C and then heating it up to the reducing temperature. The structure of the catalyst was modified, and there was an increase in the conversion of ruthenium into the alloyed state and an increase in particle size with the ascension of heat treatment temperature. In addition, the stability of the catalyst was improved after heat treatment.

关键词： catalyst prepared     stability     ascension     potentiostatic polarization     platinum-ruthenium    

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Removal of Ni(II) ions from wastewater by micellar enhanced ultrafiltration using mixed surfactants

Amar D. Vibhandik, Kumudini V. Marathe

《化学科学与工程前沿（英文）》 2014年 第8卷 第1期   页码 79-86 doi: 10.1007/s11705-014-1407-0

摘要： Ni(II) ions were removed from aqueous waste using micellar enhanced ultrafiltration (MEUF) with a mixture of surfactants. The surfactant mixture was the nonionic surfactant Tween 80 (TW80) mixed with the anionic surfactant sodium dodecyl sulfate (SDS) in different molar ratios ranging from 0.1–1.5. The operational variables of the MEUF process such as pH, applied pressure, surfactant to metal ion ratio and nonionic to ionic surfactant molar ratio (α) were evaluated. Rejection of Ni and TW80 was 99% and 98% respectively whereas that for SDS was 65%. The flux and all resistances (fouling resistance, resistance due to concentration polarization) were measured and calculated for entire range of α respectively. A calculated flux was found to be declined with time, which was mainly attributed to concentration polarization rather than resistance from membrane fouling.

关键词： MEUF     Ni (II) ions     membrane resistance     concentration polarization     mixed surfactants    

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标题 作者 时间 类型 操作

CFD simulation on membrane distillation of NaCl solution

Zhaoguang XU, Yanqiu PAN, Yalan YU

期刊论文

Computational fluid dynamics applied to high temperature hydrogen separation membranes

Guozhao JI, Guoxiong WANG, Kamel HOOMAN, Suresh BHATIA, Jo?o C. DINIZ da COSTA

期刊论文

Spin polarization strategy to deploy proton resource over atomic-level metal sites for highly selective

期刊论文

Stress induced polarization switching and coupled hysteretic dynamics in ferroelectric materials

Linxiang WANG, Roderick MELNIK, Fuzai LV

期刊论文

Dynamic modulation performance of ferroelectric liquid crystal polarization rotators and Mueller matrix

Song ZHANG, Lelun WANG, Anze YI, Honggang GU, Xiuguo CHEN, Hao JIANG, Shiyuan LIU

期刊论文

Kinetics of enhanced adsorption by polarization for organic pollutants on activated carbon fiber

HAN Yanhe, QUAN Xie, ZHAO Huimin, CHEN Shuo, ZHAO Yazhi

期刊论文

Spontaneous polarization enhanced bismuth ferrate photoelectrode: fabrication and boosted photoelectrochemical

期刊论文

极限工程——产品开发和制造中的极化

Andrew Kusiak

期刊论文

偏振模色散对高速光码的影响

饶敏,孙小菡,张明德

期刊论文

卫星通信大型双极化中国版图赋形微带反射阵天线的优化设计

Gang ZHAO, Yong-chang JIAO, Guan-tao CHEN

期刊论文

Long-term effects of electrochemical realkalization on carbonated concrete

Peng ZHU, Ji ZHANG, Wenjun QU

期刊论文

Tracing the impact of stack configuration on interface resistances in reverse electrodialysis by in situ electrochemical impedance spectroscopy

期刊论文

A Miniature Meta-Optical System for Reconfigurable Wide-Angle Imaging and Polarization-Spectral Detection

Fei Zhang,Minghao Liao,Mingbo Pu,Yinghui Guo,Lianwei Chen,Xiong Li,Qiong He,Tongtong Kang,Xiaoliang Ma,Yuan Ke,Xiangang Luo,

期刊论文

Preparation and influence of performance of anodic catalysts for direct methanol fuel cell

WANG Zhenbo, YIN Geping, SHI Pengfei

期刊论文

Removal of Ni(II) ions from wastewater by micellar enhanced ultrafiltration using mixed surfactants

Amar D. Vibhandik, Kumudini V. Marathe

期刊论文