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New electromagnetic variable flow device for slab continuous casting mold: mechanical design and magnetic field analysis

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Journal of Iron and Steel Research International 2024年第11期31卷 2710-2726页

作者： Xi-qing Chen Pu Wang Shun Liu Hong Xiao Lin-lin Lei Jia-quan Zhang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing100083China hunan Zhongke Electric Co. Ltd.Yueyang414000HunanChina MCC Capital Engineering&Research Incorporation Limited Beijing100176China

Obtaining a reasonable mold flow field for casting slabs with different sections is challenging by solely modifying the nozzle structure and continuous casting process. Research was conducted on small-sectioned (1000 mm × 220 mm) and large-sectioned (3250 mm × 220 mm) slab continuous casting molds with a fixed nozzle form (concave bottom nozzle, side port inclination angle of 0°). A three-dimensional electromagnetic model is established to analyze the current frequency, installation position, and rotation angle under the active deceleration mode and acceleration mode. The results indicate that, regardless of the deceleration mode for small-sectioned slabs or the acceleration mode for large-sectioned slabs, the magnetic flux density in the mold decreases with increasing current frequency. However, the maximum electromagnetic force initially increases and then decreases, suggesting that both electromagnetic modes have the same optimal current frequency (3 Hz). The optimal mechanical design parameters for the deceleration mode of electromagnetic variable flow device (EM-VFD) with the small-sectioned slab are as follows: installation position Z = 115 mm and rotation angle of 15°, ensuring that the maximum electromagnetic force is applied to the nozzle jet area. For the acceleration mode of the large-sectioned slab EM-VFD, the optimal mechanical design parameters are as follows: Z = 115 mm and rotation angle of 10°, ensuring that the maximum electromagnetic force is applied to 1/4 and 3/4 areas of the wide face. These findings indicate that the new electromagnetic variable flow device, which can actively adjust the flow rate and angle of the steel even under given working conditions, provides the possibility for reasonable control of the mold’s flow field.

关键词： Electromagnetic variable flow device Deceleration mode Acceleration mode Current frequency Installation position Rotation angle

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The determinants of effective defluorination by the LiAl-LDHs

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Journal of Environmental Sciences 2023年第4期126卷 153-162页

作者： Kaizhong Li Hui Liu Shuimei Li Qingzhu Li Shengtu Li Qingwei Wang School of Metallurgy and Environment Central South UniversityChangsha 410083China Chinese National Engineering Research Center for Control&Treatment of Heavy Metal Pollution Changsha 410083China Water Pollution Control Technology Key Lab of hunan province Changsha 410004China

Millions of people in poor areas are still under the threat of fluoride *** to effectively separate fluorine in water is an important step to reduce the ecological *** this paper,we performed a systematic DFT calculation focused on the defluorination behavior between the LiAl-and *** results indicated that the LiAl-LDHs exhibited high chemical activity before the defluorination,because of the better electronic *** the defluorination,the LiAl-LDHs with adsorbed-F–were also more stable than the *** addition,the existence of coordination covalent bond for the adsorbed-F–attached to the LiAl-LDHs was *** is an important reason for the high defluorination efficiency by the *** addition,a series of weak interaction,including hydrogen bond and van der Waals interaction were also ***,a LiAl-LDHs with excellent fluoride removal properties were synthesized well by simple hydrothermal *** results showed that our synthesized LiAl-LDHs with the capacity of 156.09 mg/g,could be effectively defluorinated in ***,it surpasses most materials and has potential applications.

关键词： Efficient Defluorination Water treatment LDHs DFT

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Neurogranin as an important regulator in swimming training to improve the spatial memory dysfunction of mice with chronic cerebral hypoperfusion

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Journal of Sport and Health Science 2023年第1期12卷 116-129页

作者： Huawei Lin Jiayong Zhang Yaling Dai Huanhuan Liu Xiaojun He Lewen Chen Jing Tao Chaohui Li Weilin Liu College of Rehabilitation Medicine Fujian University of Traditional Chinese MedicineFuzhou 350122China Rehabilitation Industry Institute Fujian University of Traditional Chinese MedicineFuzhou 350122China General surgery Anxi General Hospital of Traditional Chinese MedicineQuanzhou 362400China

Background:Vascular cognitive impairment caused by chronic cerebral hypoperfusion(CCH)has become a hot issue *** exercise positively contributes to the preservation or restoration of cognitive abilities;however,the specific mechanism has remained *** recent studies found that neurogranin(Ng)is a potential biomarker for cognitive *** study aims to investigate the underlying role of Ng in swimming training to improve cognitive ***:To test this hypothesis,the clustered regularly interspaced short palindromic repeats(CRISPR)-associated protein 9(Cas9)system was utilized to construct a strain of Ng conditional knockout(Ng cKO)mice,and bilateral common carotid artery stenosis(BCAS)surgery was performed to prepare the *** Experiment 1,2-month-old male and female transgenic mice were divided into a control group(wild-type littermate,n=9)and a Ng cKO group(n=9).Then,2-month-old male and female C57BL/6 mice were divided into a sham group(C57BL/6,n=12)and a BCAS group(n=12).In Experiment 2,2-month-old male and female mice were divided into a sham group(wild-type littermate,n=12),BCAS group(n=12),swim group(n=12),BCAS+Ng cKO group(n=12),and swim+Ng cKO group(n=12).Then,7 days after BCAS,mice were given swimming training for 5 weeks(1 week for adaptation and 4 weeks for training,5 days a week,60 min a day).After intervention,laser speckle was used to detect cerebral blood perfusion in the mice,and the T maze and Morris water maze were adopted to test their spatial ***,electrophysiology and Western blotting were conducted to record long-term potential and observe the expressions of Ca^(2+)pathway-related proteins,*** was applied to analyze the expression of relevant markers in neuronal damage,inflammation,and white matter ***:The figures showed that spatial memory impairment was detected in Ng cKO mice,and a sharp decline of cerebral blood flow and an impairment of p

关键词： Neurogranin Swimming training Synaptic plasticity Vascular cognitive impairment

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Rapid interrogation of special nuclear materials by combining scattering and transmission nuclear resonance fluorescence spectroscopy

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Nuclear Science and Techniques 2021年第8期32卷 67-77页

作者： Hao-Yang Lan Tan Song Jia-Lin Zhang Jian-Liang Zhou Wen Luo School of Nuclear Science and Technology University of South ChinaHengyang 421001China National Exemplary Base for International Sci.&Tech. Collaboration of Nuclear Energy and Nuclear SafetyUniversity of South ChinaHengyang 421001China

The smuggling of special nuclear materials(SNMs)across national borders is becoming a serious threat to nuclear *** paper presents a feasibility study on the rapid interrogation of concealed SNMs by combining scattering and transmission nuclear resonance fluorescence(s NRF and t NRF)*** s NRF spectroscopy,SNMs such as^(235,238)U are excited by a wide-band photon beam of appropriate energy and exhibit unique NRF *** Carlo simulations show that one-dimensional scans can realize isotopic identification of concealed^(235,238)U when the detector array used for interrogation has sufficiently high energy *** simulated isotopic ratio^(235U/238)U is in good agreement with the theoretical value when the SNMs are enclosed in relatively thin *** interrogation is followed by t NRF spectroscopy using a narrow-band photon beam with the goal of obtaining tomographic images of the concealed *** reconstructed image clearly reveals the position of the isotope^(235)U inside an iron *** is shown that the interrogation time of s NRF and t NRF spectroscopy is one order of magnitude lower than that when only t NRF spectroscopy is used and results in a missed-detection rate of 10^(-3).The proposed method can also be applied for isotopic imaging of other SNMs such as^(239,240)Pu and^(237)Np.

关键词： Special nuclear material Nondestructive interrogation Nuclear resonance fluorescence

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Recent progress in fluorinated electrolytes for improving the performance of Li–S batteries

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Journal of Energy Chemistry 2020年第2期29卷 149-170页

作者： Xiwen Wang Yuqing Tan Guohong Shen Shiguo Zhang College of Materials Science and Engineering State Key Laboratory of Advanced Design and Manufacturing for Vehicle BodyHunan UniversityChangsha 410082HunanChina

Lithium–sulfur(Li–S) batteries represent a "beyond Li-ion" technology with low cost and high theoretical energy density and should fulfill the ever-growing requirements of electric vehicles and stationary energy storage systems. However, the sulfur-based conversion reaction in conventional liquid electrolytes results in issues like the so-called shuttle effect of polysulfides and lithium dendrite growth, which deteriorate the electrochemical performance and safety of Li–S batteries. Optimization of conventional organic solvents(including ether and carbonate) by fluorination to form fluorinated electrolytes is a promising strategy for the practical application of Li–S batteries. The fluorinated electrolytes, owing to the high electronegativity of fluorine, possesses attractive physicochemical properties, including low melting point,high flash point, and low solubility of lithium polysulfide, and can form a compact and stable solid electrolyte interphase(SEI) with the lithium metal anode. Herein, we review recent advancements in the development of fluorinated electrolytes for use in Li–S batteries. The effect of solvent molecular structure on the performance of Li–S batteries and the formation mechanism of SEI on the cathode and anode sides are analyzed and discussed in detail. The remaining challenges and future perspectives of fluorinated electrolytes for Li–S batteries are also presented.

关键词： Lithium–sulfur batteries Electrolyte Fluorinated solvents Shuttle effect SEI forming mechanism

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Sliding Mode Control Design for a Class of Systems with Mismatched Uncertainties

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自动化学报 2005年第5期31卷 136-140页

作者： XIANG Ji SU Hong-Ye CHU Jian (National Laboratory of Industrial Control Technology,Institute of Advanced Process Control,Zhejiang University,Yuquan Campus,Hangzhou 310027) Institute of Advanced Process Control Zhejiang University Yuquan Campus National Laboratory of Industrial Control Technology 浙江 Hangzhou 310027

A new sliding mode controller design method is proposed for a class of system with mis- matched uncertainties such that the dynamic function restricted on the sliding surface is completely insensitive to the uncertainties.A sufficient and necessary condition which the system possessing this sliding mode controller should satisfy is explicitly *** issue of chattering free is also *** is concluded that this class of mismatched term does not bring any chattering problem. Finally,a numerical example illustrates the developed method.

关键词： Sliding mode control(SMC) uncertain system mismatched uncertainty

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Improved photocatalytic performance of gradient reduced TiO2 ceramics with aligned pore channels

Advanced Powder Materials

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Advanced Powder Materials 2022年第3期1卷 27-34页

作者： Hanyu Gong Lu Wang Kechao Zhou Dou Zhang Yan Zhang Vana Adamaki Aleksandrs Sergejevs Chris Bowen State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Department of Mechanical Engineering University of BathBA27AYUK Electronic and Electrical Engineering Department University of BathBA27AYUK

Magn-eli,a fascinating sub-stoichiometric titanium oxide phase that contains oxygen vacancies of TiO_(2),is proposed as a potential photo-electrode for photocatalysis due to its high conductivity and photoelectric conversion *** this work,partially reduced porous TiO_(2) ceramics with a graded reduction profile and an aligned pore structure were prepared by carbo-thermal reduction of freeze-cast TiO_(2) with a range of porosities from 10 to 30 vol.%.AC conductivity evaluation revealed that the oxygen vacancies that exist in Magn-eli lead to a relatively high AC conductivity of~10 S/m at 1 kHz,as compared to that of the stoichiometric porous TiO_(2).A maximum photocurrent density and incident photon-to-current efficiency(IPCE)of 9.14 mA/cm^(2) and 40.52%respectively were achieved from the gradient porous Magn-eli with a porosity of 30 vol.%.

关键词： TiO_(2)ceramics Magneli Photocatalysis Aligned pore

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Novel rockburst prediction criterion with enhanced explainability employing CatBoost and nature-inspired metaheuristic technique

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Underground Space 2024年第6期19卷 101-118页

作者： Yingui Qiu Jian Zhou School of Resources and Safety Engineering Central South UniversityChangsha 410083China

Rockburst is a major challenge to hard rock engineering at great *** and timely assessment of rockburst risk can avoid unnecessary casualties and property *** the existence of various methods for rockburst assessment,there remains an urgent need for a comprehensive and reliable criterion that is easy to both apply and *** a new rockburst criterion based on simple parameters can potentially fill this *** its advantages,this criterion can facilitate a more effective and efficient prediction of rockburst potential,thereby contributing significantly to enhancing safety *** this paper,combined with the internal and external factors of rockburst,four control variables(i.e.,integrity index,stress index,brittleness index,and elastic energy index)were selected to be incorporated into a comprehensive rockburstability index(RBSI).Based on 116 sets of rockburst cases,the rockburst potential was accurately quantified and predicted using the categorical boosting(CatBoost)model and the nature-inspired metaheuristic African vultures optimization algorithm(AVOA).In its performance validation,the criterion achieved the highest accuracy of 90.48%,verifying the reliability and effectiveness of the proposed RBSI ***,an interpretive method was applied to analyze the variable influence on the criterion,facilitating the explanation of predictions and the analysis of the formula’s robustness under different *** general,compared with existing criterion methods involving relevant indicators,the newly proposed RBSI criterion enhances the accuracy of rockburst potential prediction,and it can effectively and swiftly evaluate the preliminary risk of ***,a graphical user interface was developed to provide a clear visualization of the assessment of rockburst potential.

关键词： Rockburst criterion CatBoost Metaheuristic optimization Model interpretation Graphical user interface

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Self-standing 3D nanoporous Ag_(2)Al with abundant surface oxygen species facilitating oxygen electroreduction for efficient hybrid Zn battery

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Journal of Energy Chemistry 2021年第7期30卷 345-354页

作者： Ming Peng Yang Zhao Jiao Lan Yijin Qiao Yongwen Tan College of Materials Science and Engineering Hunan UniversityChangsha 410082HunanChina

The hybrid battery integrating a typical Zn redox battery and a Zn-air battery is a promising green technology for energy storage,and the cathode integrating the redox reaction and electrocatalytic oxygen reduction is a key point for efficient electrochemical energy ***,we report a scalable strategy to fabricate nanoporous Ag2 Al internetallic compound as a self-standing cathode for the hybrid Zn *** abundant surface oxygen species,the Ag-Al intermetallic interaction and the npAg_(2)Al@AgAlOx interface cooperatively contributed to the catalytic ORR *** electrode endows efficient catalytic oxygen reduction(a Tafel slope of 38.0 mV/dec and an onset potential of 0.998 V)and regulated redox activity as compared with *** nanoporous channels allow efficient ion transport,interface charge exchange and gas molecular ***,the assembled hybrid Zn-Ag_(2) Al/air battery delivers a high capacity of 3.23 mAh/cm^(2) as compared with recent *** far as we know,this is the first exploration for the electrochemical property of Ag2 Al,and it would inspire more exploration in developing multifunctional materials and robust hybrid batteries for practical applications.

关键词： Nanoporous metal Ag_(2)Al Oxygen reduction Intermetallic interaction Hybrid battery

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Enhanced Efficiency of Dye-sensitized Solar Cells Using rGO@TiO2 Nanotube Hybrids

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Chemical Research in Chinese Universities 2018年第2期34卷 269-273页

作者： LIU Rui QIAO Yingjie SONG Yingjin SONG Kehan LIU Chuan School of Science Harbin University of Commerce Harbin 150076 P. R. China College of Materials Science and Chemical Engineering Harbin Engineering University Harbin 150001 P R. China Department of Chemistry Harbin University Harbin 150050 P. R. China Department of Chemistry Qiqihar University Qiqihar 161006 P. R. China

We established a novel strategy for the synthesis of reduced graphene oxide（rGO）@TiO2 nanotube hybrids using an 18 W UV-assisted photo-catalytic reduction method for utilization as photo-anode of dye-sensitized solar cells（DSSCs）. The photo-conversion efficiency of DSSCs was significantly enhanced after the addition of rGO, and in addition, the photo-anode showed decreased internal resistance. Analysis of rGO@TiO2 hybrids by transmissions scanning electron microscopy（TEM）, X-ray diffraction（XRD）, Raman spectra, N2 adsorption and desorption, atomic force microscopy（AFM） and X-ray photoelectron speetroscopy（XPS） demonstrates that the rGO modified TiO2 nanotubes can increase the short-circuit current and the conversion efficiency of dye-sensitized solar cells. The efficiency is improved by almost two folds as much compared to those of the bare TiO2 nanotubes.

关键词： TiO2 nanotube array, Reduced graphene oxide(rGO) Hybrid Dye-sensitized solar eell(DSSC)

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