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A new 4-Ti-added polyoxometalate

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Tungsten 2024年第2期6卷 465-471页

作者： Hai-Lou Li chen Lian Guo-yu Yang MOE Key Laboratory of Cluster Science School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 102488China

A new inorganic–organic hybrid 4-Ti-added polyoxometalate:[H_(2)N(CH_(3))_(2)]_(2)Na_(3)H_(5)[{Ti(C_(2)O_(4))(H_(2)O)}_(2){Ti(C_(2)O_(4))}_(2)(B-β-SbW_(9)O_(33))_(2)]·22H_(2)O(1)has been successfully made and further characterized by infrared spectroscopy,thermogravimetric analysis,powder X-ray diff raction and single-crystal X-ray diff *** polyoxoanion of 1 exhibits a Krebs-type structure that is constructed from two[B-β-SbW_(9)O_(33)]^(9)−fragments fused together by a belt of four additional Ti atoms decorated by oxalate ***,1 as a heterogeneous catalyst exhibits high activity for Knoevenagel condensation under mild reaction conditions.

关键词： Polyoxometalate Ti-added POM Krebs-type structure Knoevenagel condensation

Physics-informed deep Koopman operator for Lagrangian dynamic systems

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Science China(Information Sciences) 2024年第09期67卷 146-163页

作者： Xuefeng WANG Yang CAO Shaofeng chen yu KANG Department of Automation University of Science and Technology of China State Key Laboratory of Fire Science University of Science and Technology of China Institute of Advanced Technology University of Science and Technology of China

Accurate mechanical system models are crucial for safe and stable control. Unlike linear systems,Lagrangian systems are highly nonlinear and difficult to optimize because of their unknown system *** research thus used deep neural networks to generate linear models of original systems by mapping nonlinear dynamic systems into a linear space with a Koopman observable function encoder. The controller then relies on the Koopman linear model. However, without physical information constraints, ensuring control consistency between the original nonlinear system and the Koopman system is tough, as the learning process of the Koopman observation function is unsupervised. This paper thus proposes a two-stage learning algorithm that uses structural subnetworks to build a physics-informed network topology to simultaneously learn the Koopman observable functions and the system energy representation. In the Koopman matrix learning session, a quadratic-constrained optimization problem is solved to ensure that the Koopman representation satisfies the energy difference matching hard constraint. The proposed energy-preserving deep Lagrangian Koopman(EPDLK) framework effectively represents the dynamics of the Lagrangian system while ensuring control consistency. The effectiveness of EPDLK is compared with those of various Koopman observable function construction methods in multistep prediction and trajectory tracking tasks. EPDLK achieves better control consistency by guaranteeing energy difference matching, which facilitates the application of the control law generated on the Koopman system directly to the original nonlinear Lagrangian system.

关键词： Koopman operator Lagrangian physics-informed nonlinear model predictive control (MPC)

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Etching Mechanism of Ti_(3)C_(2)Cl_(2) MXene Phases by CuCl_(2)-Lewis Molten Salt Method

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Journal of Wuhan University of Technology(Materials Science) 2024年第4期39卷 863-868页

作者：严明 ZHU yu HUANG Jiangtao chen Haoyu DENG yuxiao chen Yanlin 王娟 Jan-Michael Albina Hubei Provincial Key Laboratory of Green Materials for Light Industry Hubei University of TechnologyWuhan 430068China New Materials and Green Manufacturing Talent Introduction and Innovation Demonstration Base Hubei University of TechnologyWuhan 430068China Hubei Longzhong Laboratory Xiangyang 441000China

We described a method for obtaining fluorine-free Ti_(3)C_(2)Cl_(2)MXene phases by melting copper in CuCl_(2)instead of aluminum in Ti_(3)AlC_(2).XRD results show that when molten salt CuCl_(2)etches Ti_(3)AlC_(2),it forms an intermediate product Ti_(3)CuC_(2),and then reacts with Ti_(3)CuC_(2)to obtain Ti_(3)C_(2)Cl_(2).The reaction of Ti_(3)AlC_(2)and CuCl_(2)at a temperature of 800℃for 2 h to obtain Ti_(3)C_(2)Cl_(2)with an optimal lamellar structure is shown in SEM *** pseudopotential plane-wave(PP-PW)method is used to calculate on the electronic *** etching mechanism is investigated by the total energies of each *** chemical reaction of Ti_(3)AlC_(2)and CuCl_(2)will first become Ti_(3)CuC_(2)and Cu,and then become Ti_(3)C_(2)Cl_(2)during the Lewis acid etching process,which are consistent with the experimental results.

关键词： molten salt method CuCl_(2) MXene first-principles calculations etching mechanism

Stochastic Flexibility Evaluation for Virtual Power Plants by Aggregating Distributed Energy Resources

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 988-999页

作者： Siyuan Wang Wenchuan Wu Qizhan chen Junjie yu Peng Wang Department of Electrical Engineering Tsinghua UniversityBeijing 100084China Zhongshan Power Supply Bureau of the Guangdong Power Grid Corporation Zhongshan 528400China Beijing Qingda Gaoke System Control Company Beijing 102208China CSEE IEEE

To manage a large amount of flexible distributed energy resources(DERs)in the distribution networks,the virtual power plant(VPP)is introduced into the *** VPP can optimally dispatch these resources in a cluster manner and provide flexibility for the power system operation as a *** existing studies formulate the equivalent power flexibility of the aggregating DERs as deterministic optimization models without considering their *** this paper,we introduce the stochastic power flexibility range(PFR)and timecoupling flexibility(TCF)to describe the power flexibility of *** this model,both operational constraints and the randomness of the DERs’output are incorporated,and a combined model and data-driven solution is proposed to obtain the stochastic PFR,TCF,and cost function of *** aggregating model can be easily incorporated into the optimization model for the power system operator or market bidding,considering ***,a numerical test is *** results show that the proposed model not only has higher computational efficiency than the scenario-based methods but also achieves more economic benefits.

关键词： Chance constrained optimization combined model and data-driven stochastic power flexibility virtual power plant

The variation of microbiological characteristics in surface waters during persistent precipitation

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FRONTIERS OF ENVIRONMENTAL SCIENCE & ENGINEERING 2024年第9期18卷 111-0页

作者： Xiao, Xinyan chen, chenlan Li, Haoran Li, Lihua yu, Xin Xiamen Univ Coll Environm & Ecol Xiamen 361102 Peoples R China Xiamen Univ Fujian Key Lab Coastal Pollut Prevent & Control Xiamen 361102 Peoples R China

Climate change leads to an increase in both the frequency and intensity of extreme precipitation. Surface runoff generated by extreme precipitation has a significant impact on water. However, the impact of persistent precipitation on surface water quality is easy to neglect, due to its prolonged duration and lower-intensity rainfall. This study established eight sampling points within selected surface waters to observe the variation of microbial characteristics in a typical persistence precipitation event. The primary difference between Furong Lake (FL) and chengqian Reservoir (CR) was: the concentrations of dissolved organic carbon (DOC) were 21.3 +/- 0.7 and 8.3 +/- 1.5 mg/L in FL and CR, respectively. The concentrations of R2A culturable bacteria and coliforms were 10(4.57) and 10(1.58) colony-forming units (CFU)/mL in FL, and were 10(5.46) and 10(2.64) CFU/mL in CR, respectively. During precipitation, the maximum increase concentrations of R2A, NA culturable bacteria, and coliforms were 10(0.75), 10(1.30), and 10(2.27) CFU/mL in FL, respectively. Furthermore, microbial concentration and rainfall did not increase simultaneously, and a delay phenomenon was observed in the increasing microbial concentrations. Through analyzing the concentration change trends and correlation of various water quality indicators during persistent precipitation, the significant correlation between the DOC concentration and the changes in the dominant species of microbial community structure was found in this study (p < 0.05). For example, as the DOC concentration declined, the abundance of hgcl_clade and CL500-29_marine_group increased. Consequently, although persistent precipitation might not obviously alter the water quality visibly, it could still pose potential microbial risks.

关键词： Rainfall Dissolved organic carbon Culturable bacteria Water quality Microbial community structure Climate change ESCHERICHIA-COLI EXTREME PRECIPITATION AEROMONAS-HYDROPHILA URBAN QUALITY RIVER STORMWATER EXPOSURE RAINFALL EVENTS

In situ generation of oxyanions-decorated cobalt(nickel)oxyhydroxide catalyst with high corrosion resistance for stable and efficient seawater oxidation

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Journal of Energy Chemistry 2024年第7期94卷 508-516页

作者： Fengting Luo Pei yu Jueting Xiang Junjie Jiang Shijian chen Chongqing Key Laboratory of Interface Physics in Energy Conversion College of PhysicsChongqing UniversityChongqing 401331China Center of Modern Physics Institute for Smart City of Chongqing University in LiyangLiyang 213300JiangsuChina

The development of efficient and robust anode materials for stable alkaline seawater electrolysis is severely limited by chlorine evolution reaction and chloride ***,the sulfur-doped cobalt-nickel bimetallic phosphides(CoNiPS)are specifically designed as a pre-catalyst for navigating a surface reconstruction to fabricate the anions(PO^(3-)_(4) and SO^(2-)_(4))-decorated Co(Ni)OOH catalyst(R-CoNiPS)with exceptional durability and high activity for stable alkaline seawater oxidation(ASO).Various experiment techniques together with theoretical simulations both demonstrate that the in situ-generated PO^(3-)_(4) and SO^(2-)_(4) anions on catalyst surface can improve the oxygen evolution reaction(OER)activity,regulating and stabilizing the catalytic active species Co(Ni)OOH,as well as make a critical role in inhibiting the adsorp-tion of chloride ions and extending the service life of ***,this R-CoNiPS electrode exhi-bits superb OER activity toward AsO and stands out among the non-precious ASO electrocatalysts reported recently,requiring low overpotentials of 420 and 440 mV to attain large current densities of 500 and 1000 mA cm^(-2) in an alkaline natural seawater electrolyte,***,the catalyst displays a negligible chloride corrosion at room temperature during ASO operation(>200 h)at 500 mA cm^(-2).This work opens up a new viewpoint for designing high-activity and durable electrocata-lystsforseawaterelectrolysis.

关键词： Seawater electrolysis Anions Oxygen evolution reaction Chloride corrosion

Pyridine-regulated Sb@InSbS_(3)ultrafine nanoplates as high-capacity and long-cycle anodes for sodium-ion batteries

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Rare Metals 2024年第5期43卷 2080-2092页

作者： Jia-Ying Ren Xiang-Lin yu Chang-Miao chen Xin-yu Hu Ting Yang Ming Zhang College of Materials Science and Engineering and College of Science Central South University of Forestry and TechnologyChangsha 410004China College of Semiconductors(College of Integrated Circuits) Changsha Semiconductor Technology and Application Innovation Research InstituteHunan UniversityChangsha 410082China

Sb-based materials exhibit considerable potential for sodium-ion storage owing to their high theoretica ***,the bulk properties of Sb-based materials always result in poor cycling and rate *** overcome these issues,pyridine-regulated Sb@InSbS_(3)ultrafine nanoplates loaded on reduced graphene oxides(Sb@InSbS_(3)@rGO)were designed and *** the synthesis process,pyridine was initially adopted to coordinate with In^(3+),and uniformly dispersed In_(2)S_(3)ultrafine nanoplates on reduced graphene oxide were generated after ***,partial In^(3+)was exchanged with Sb^(3+),and Sb@InSbS_(3)@rGO was obtained by using the subsequent annealing *** unique structure of Sb@InSbS_(3)@rGO effectively shortened the transfer path of sodium ions and electrons and provided a high *** the anode in sodium-ion batteries,the Sb@InSbS_(3)@rGO electrode demonstrated a significantly higher reversible capacity better stability(445 m Ah·g^(-1)at 0.1 A·g^(-1)after 200 cycles and 212 mAh·g^(-1)at 2 A·g^(-1)after 1200 cycles),and superior rate(210 mAh·g^(-1)at 6.4 A·g^(-1))than the electrode without pyridine(355 mAh·g-1at 0.1 A·g-1after 55 cycles and 109 mAh·g^(-1)at 2 A·g^(-1)after 770 cycles)Furthermore,full cells were assembled by using the Sb@InSbS_(3)@rGO as anode and Na_(3)V_(2)(PO_(4))_(3)as cathode which demonstrated good cycling and rate performances and exhibited promising application *** results indicate that adjusting the microstructure of electrode materials through coordination balance is A·good strategy for obtaining high-capacity,high-rate,and longcycle sodium storage performances.

关键词： Sodium-ion battery Sb-based anode material Pyridine coordination Reduced size nanostructure Half/full cell

SUMS OF DUAL TOEPLITZ PRODUCTS ON THE ORTHOGONAL COMPLEMENTS OF FOCK-SOBOLEV SPACES

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Acta Mathematica Scientia 2024年第3期44卷 810-822页

作者：陈泳 Young Joo lee Department of Mathematics Hangzhou Normal UniversityHangzhou311121China Department of Mathematics Chonnam National UniversityGwangju61186Korea

We consider dual Toeplitz operators on the orthogonal complements of the FockSobolev spaces of all nonnegative real ***,for symbols in a certain class containing all bounded functions,we study the problem of when an operator which is finite sums of the dual Toeplitz products is compact or ***,for bounded symbols,we construct a symbol map and exhibit a short exact sequence associated with the C^(*)-algebra generated by all dual Toeplitz operators with bounded symbols.

关键词： dual Toeplitz operators Fock-Sobolev spaces symbol map

Defect-mode and Fabry-Perot resonance induced multi-band nonreciprocal thermal radiation

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Science China(Technological Sciences) 2024年第8期67卷 2405-2412页

作者： chen ZiHe yu ShiLv yuAN cheng CUI XinYou HU Run School of Energy and Power Engineering Huazhong University of Science and TechnologyWuhan 430074China Wuhan Fiberhome Fuhua Electric Co. Ltd.Wuhan 430074China

According to Kirchhoff's radiation law,the spectral-directional absorptivity(α)and spectral-directional emissivity(e)of an object are widely believed to be identical,which places a fundamental limit on photonic energy conversion and *** introduction of Weyl semimetals and magneto-optical(MO)materials into photonic crystals makes it possible to violate Kirchhoff's law,but most existing work only report the unequal absorptivity and emissivity spectra in a single band,which cannot meet the requirements of most practical ***,we introduce a defect layer into the structure composed of one-dimensional(1D)magnetophotonic crystal and a metal layer,which realizes dual-band nonreciprocal thermal radiation under a 3-T magnetic field with an incident angle of 60°.The realization of dual-band nonreciprocal radiation is mainly due to the Fabry-Perot(FP)resonance occurring in the defect layer and the excitation of Tamm plasmon,which is proved by calculating the magnetic field *** addition,the effects of incident angle and structural parameters on nonreciprocity are also *** is more,the number of nonreciprocal bands could be further increased by tuning the defect layer *** the defect layer thickness increases to 18.2μm,tri-band nonreciprocal thermal radiation is realized due to the enhanced number of defect modes in the photonic band gap and the FP resonance occurring in the defect ***,the effect of defect location on nonreciprocity is also *** present work provides a new way for the design of multi-band or even broad-band nonreciprocal thermal emitters.

关键词： Kirchhoff's law multi-band nonreciprocal thermal radiation magnetophotonic crystal Tamm plasmon defect layer Fabry-Perot resonance