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Long-term operation optimization of circulating cooling water systems under fouling conditions

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Chinese Journal of Chemical Engineering 2024年第1期65卷 255-267页

作者： Jiarui Liang yong Tian Shutong Yang yong Wang Ruiqi Yin Yufei Wang School of Chemical Engineering and Environment China University of PetroleumBeijing102249China CHN Energy Xinjiang Chemical Co. LTDUrumqi830092China College of Mechanical and Transportation Engineering China University of PetroleumBeijing 102249China

Fouling caused by excess metal ions in hard water can negatively impact the performance of the circulating cooling water system(CCWS)by depositing ions on the heat exchanger's ***,the operation optimization of CCWS often prioritizes short-term flow velocity optimization for minimizing power consumption,without considering ***,low flow velocity promotes ***,it's crucial to balance fouling and energy/water conservation for optimal CCWS long-term *** study proposes a mixed-integer nonlinear programming(MINLP)model to achieve this *** model considers fouling in the pipeline,dynamic concentration cycle,and variable frequency drive to optimize the synergy between heat transfer,pressure drop,and *** optimizing the concentration cycle of the CCWS,water conservation and fouling control can be *** model can obtain the optimal operating parameters for different operation intervals,including the number of pumps,frequency,and valve local resistance *** experiments on cycle and environmental temperature reveal that as the cycle increases,the marginal benefits of energy/water conservation *** periods with minimal impact on fouling rate,energy/water conservation can be achieved by increasing the cycle while maintaining a low fouling ***,the proposed model has significant energy/water saving effects and can comprehensively optimize the CCWS through its incorporation of fouling and cycle optimization.

关键词： Computer simulation Circulating water system Fouling Concentration cycle Optimization Variable frequency drive

Planar matrices and arrays of Feynman diagrams:poles for higher k

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Communications in Theoretical Physics 2024年第4期76卷 1-13页

作者： Alfredo Guevara yong Zhang Perimeter Institute for Theoretical Physics WaterlooON N2L 2Y5Canada Department of Physics&Astronomy University of WaterlooWaterlooON N2L 3G1Canada Society of Fellows Harvard UniversityCambridgeMA 02138United States of America CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesNo.19A Yuquan RoadBejing 100049China

Planar arrays of tree diagrams were introduced as a generalization of Feynman diagrams that enable the computation of biadjoint amplitudes m_(n)(^(k))for k>*** this follow-up work,we investigate the poles of m_(n)(^(k))from the perspective of such *** general k,we characterize the underlying polytope as a Flag Complex and propose a computation of the amplitude-based solely on the knowledge of the poles,whose number is drastically less than the number of the full *** an example,we first provide all the poles for the cases(k,n)=(3,7),(3,8),(3,9),(3,10),(4,8)and(4,9)in terms of their planar arrays of degenerate Feynman *** then implement simple compatibility criteria together with an addition operation between arrays and recover the full collections/arrays for such *** the way,we implement hard and soft kinematical limits,which provide a map between the poles in kinematic space and their combinatoric *** use the operation to give a proof of a previously conjectured combinatorial duality for arrays in(k,n)and(n-k,n).We also outline the relation to boundary maps of the hypersimplex Δ_(k,n) and rays in the tropical Grassmannian Tr(k,n).

关键词： Feynman diagrams biadjoint amplitudes poles

The Essential 2-rank for Classical Groups

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Acta Mathematica Sinica,English Series 2024年第9期40卷 2169-2186页

作者： Jian Bei AN yong XU Department of Mathematics University of AucklandAucklandNew Zealand School of Mathematics and Statistics He’nan University of Science and TechnologyLuoyang 471023P.R.China

Let G be a symplectic or orthogonal group defined over a finite field with odd characteristic and let D≤G be a Sylow *** this paper,we classify the essential 2-subgroups and determine the essential 2-rank of the Frobenius category FD(G).Together with the results of An–Dietrich and Cao–An–Zeng,this completes the work of essential subgroups and essential ranks of classical groups.

关键词： Frobenius category conjugation families essential 2-rank symplectic groups orthogonal groups

Concise extraction and characterization of the pore-throat network in unconventional hydrocarbon reservoirs: A new perspective

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Petroleum Science 2024年第3期21卷 1474-1487页

作者： Shu-Heng Du yong-Min Shi State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing100190China School of Engineering Science University of Chinese Academy of SciencesBeijing100049China School of Earth and Space Sciences Peking UniversityBeijing100871China

In this study,a new image-based method for the extraction and characterization of pore-throat network for unconventional hydrocarbon storage and exploitation is proposed.“Pore-throat solidity”,which is analogous to particle solidity,and a new method for automatic identification of pores and throats in tight sandstone oil reservoirs are ***,the“pore-throat combination”and“pure pore”are defined and distinguished by drawing the cumulative probability curve of the pore-throat solidity and by selecting an appropriate cutoff *** the discrete grid set is recognized as a pore-throat combination,Legendre ellipse fitting and minimum Feret diameter are *** the pore and throat grid sets are identified as pure pores,the pore diameter can be directly *** the new method,the analytical results for the physical parameters and pore radius agree well with most prior *** results comparing the maximum ball and the new model could also prove the accuracy of the latter's in micro and nano *** new model provides a more practical theoretical basis and a new calculation method for the rapid and accurate evaluation of the complex processes of oil migration.

关键词： Hydrocarbon exploitation Pore Throat Porous media Identification

Physics-Informed Neural Networks with Two Weighted Loss Function Methods for Interactions of Two-Dimensional Oceanic Internal Solitary Waves

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Journal of Systems Science & Complexity 2024年第2期37卷 545-566页

作者： SUN Junchao CHEN yong TANG Xiaoyan School of Mathematical Sciences Key Laboratory of Mathematics and Engineering Applications(Ministry of Education)&Shanghai Key Laboratory of PMMPEast China Normal UniversityShanghai 200241China College of Mathematics and Systems Science Shandong University of Science and TechnologyQingdao 266590China

The multiple patterns of internal solitary wave interactions(ISWI)are a complex oceanic *** remote sensing techniques indirectly detect these ISWI,but do not provide information on their detailed structure and ***,the authors considered a three-layer fluid with shear flow and developed a(2+1)Kadomtsev-Petviashvili(KP)model that is capable of describing five types of oceanic ISWI,including O-type,P-type,TO-type,TP-type,and *** learning models,particularly physics-informed neural networks(PINN),are widely used in the field of fluids and internal solitary ***,the authors find that the amplitude of internal solitary waves is much smaller than the wavelength and the ISWI occur at relatively large spatial scales,and these characteristics lead to an imbalance in the loss function of the PINN *** solve this problem,the authors introduce two weighted loss function methods,the fixed weighing and the adaptive weighting methods,to improve the PINN *** successfully simulated the detailed structure and dynamics of ISWI,with simulation results corresponding to the satellite *** particular,the adaptive weighting method can automatically update the weights of different terms in the loss function and outperforms the fixed weighting method in terms of generalization ability.

关键词： Internal solitary wave interactions KP equation PINN method weighted loss function method

Thermodynamic model for deoxidation of liquid steel considering strong metal-oxygen interaction in the quasichemical model framework

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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 988-1002页

作者： yong-Min Cho Youn-Bae Kang Graduate Institute of Ferrous and Eco Materials Technology Pohang University of Science and TechnologyPohangKyungbuk37673Rep.of Korea N.EX.T Hub POSCO HoldingsPohangKyungbuk37673Rep.of Korea Department of Materials Science and Engineering Pohang University of Science and TechnologyPohangKyungbuk37673Rep.of Korea

Herein,a thermodynamic model aimed at describing deoxidation equilibria in liquid steel was *** model provides explicit forms of the activity coefficient of solutes in liquid steel,eliminating the need for the minimization of internal Gibbs energy preliminarily when solving deoxidation *** elimination of internal Gibbs energy minimization is particularly advantageous during the coupling of deoxidation equilibrium calculations with computationally intensive approaches,such as computational fluid *** model enables efficient calculations through direct embedment of the explicit forms of activity coefficient in the computing *** proposed thermodynamic model was developed using a quasichemical approach with two key approximations:random mixing of metallic elements(Fe and oxidizing metal) and strong nonrandom pairing of metal and oxygen as nearest *** these approximations,the quasichemical approach yielded the activity coefficients of solutes as explicit functions of composition and temperature without requiring the minimization of internal Gibbs energy or the coupling of separate *** model was successfully applied in the calculation of deoxidation equilibria of various elements(Al,B,C,Ca,Ce,Cr,La,Mg,Mn,Nb,Si,Ti,V,and Zr).The limitations of the model arising from these assumptions were also discussed.

关键词： deoxidation equilibria thermodynamics quasichemical approach computational fluid dynamics

A novel weld-pool-length monitoring method based on pixel analysis in plasma arc additive manufacturing

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Advances in Manufacturing 2024年第2期12卷 335-348页

作者： Bao-Ri Zhang yong-Hua Shi Bionic Robot Research Department Ji Hua LaboratoryFoshan528200GuangdongPeople’s Republic of China Guangdong Provincial Engineering Research Center for Special Welding Technology and Equipment School of Mechanical and Automotive EngineeringSouth China University of TechnologyGuangzhou510640People’s Republic of China

The real-time monitoring of the weld pool during deposition is important for automatic control in plasma arc additive *** obtain a high deposition accuracy,it is essential to maintain a stable weld pool *** this study,a novel passive visual method is proposed to measure the weld pool *** the proposed method,the image quality was improved by designing a special visual system that employed an endoscope and a *** also includes pixel brightness-based and gradient-based algorithms that can adaptively detect feature points at the boundary when the weld pool geometry *** algorithm can also be applied to materials with different solidification *** was performed to measure the real weld pool length in world coordinates,and outlier rejection was performed to increase the accuracy of the ***,tests were carried out on the intersection component,and the results showed that the proposed method performed well in tracking the changing weld pool length and was applicable to the real-time monitoring of different types of materials.

关键词： Plasma arc additive manufacturing(PAAM) Weld pool geometry Gradient analysis Real-time detection

p-d Orbital Hybridization Engineered Single-Atom Catalyst for Electrocatalytic Ammonia Synthesis

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Energy & Environmental Materials 2024年第2期7卷 119-125页

作者： Jingkun Yu Xue yong Siyu Lu Green Catalysis Center and College of ChemistryZhengzhou UniversityZhengzhou 450001China Department of Chemistry University of SheffieldSheffieldS37HFUK

The rational design of metal single-atom catalysts(SACs)for electrochemical nitrogen reduction reaction(NRR)is ***-dimensional metal-organic frameworks(2DMOFs)is a unique class of promising *** to now,the roles of individual metals,coordination atoms,and their synergy effect on the electroanalytic performance remain ***,in this work,a series of 2DMOFs with different metals and coordinating atoms are systematically investigated as electrocatalysts for ammonia synthesis using density functional theory *** a specific metal,a proper metal-intermediate atoms p-d orbital hybridization interaction strength is found to be a key indicator for their NRR catalytic *** hybridization interaction strength can be quantitatively described with the p-/d-band center energy difference(Δd-p),which is found to be a sufficient descriptor for both the p-d hybridization strength and the NRR *** maximum free energy change(ΔG_(max))andΔd-p have a volcanic relationship with OsC_(4)(Se)_(4)located at the apex of the volcanic curve,showing the best NRR *** asymmetrical coordination environment could regulate the band structure subtly in terms of band overlap and *** work may shed new light on the application of orbital engineering in electrocatalytic NRR activity and especially promotes the rational design for SACs.

关键词： first-principle calculations Nitrogen reduction p-d orbital hybridization single-atom catalysts

Spray characteristics of different regions downstream of a swirl cup

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Chinese Journal of Aeronautics 2024年第8期37卷 124-143页

作者： Donghui WANG yong HUANG Hongzhou ZHANG Collaborative Innovation Center of Advanced Aero-Engine School of Energy and Power EngineeringBeihang UniversityBeijing 102206China National Key Laboratory of Science and Technology School of Energy and Power EngineeringBeihang UniversityBeijing 102206China

The spray characteristics of different regions downstream of swirl cups play a critical role in cold start and re-ignition of gas *** spray measurements were performed at the fuel pressures of 0.5,0.8,1.0,1.5,and 2.0 MPa and the fuel temperatures of-23,-13,-3,7,17 and 27℃,*** droplet size,droplet velocity,droplet number,and instantaneous spatial spray image of sprays from an aviation kerosene Jet-A were measured using a two-component phase Doppler particle analyzer and a digital off-axis holography *** the fuel pressure and temperature increase,the Sauter Mean Diameter(SMD)and spray non-uniformity of the Spray Shear Layer(SSL)gradually *** the fuel pressure increases,the SMD and spray non-uniformity of the Central Toroidal Recirculation Zone(CTRZ)gradually decrease,and the slopes of these curves both *** the fuel pressure increases,the SMD and spray nonuniformity of the CTRZ rapidly decrease at the fuel temperature of23℃,while slightly decrease at the fuel temperature of 27℃.The droplets in the CTRZ come from 3 different sources:simplex nozzle,venturi,and outside the *** the fuel pressure increases,the proportion of droplets recirculated from outside the CTRZ *** study proposed the concept of the“pressure critical point”for the swirl *** the fuel temperature decreases,the proportion of droplets recirculated from outside the CTRZ increases below the critical pressure,while decreases above the critical *** addition,through the models of liquid film formation and breakup on the curved cylindrical wall,a semi-theoretical model was established to predict the SMD of SSL for swirl *** prediction uncertainty of this model is less than 6%for all 14 conditions in this paper.

关键词： Swirl cup Sauter Mean Diameter(SMD) Spray non-uniformity Atomizing regions Semi-theoretical prediction Spray nozzles