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A Note on the Entropy for Heisenberg Group Actions on the Torus

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Acta Mathematica Sinica,English Series 2024年第10期40卷 2324-2336页

作者： Yu zhang Yu jun ZHU School of Mathematical Sciences Xiamen University

In this paper,the entropy of discrete Heisenberg group actions is *** α be a discrete Heisenberg group action on a compact metric space *** types of entropies,■ and h(α)are introduced,in which ■ is defined in Ruelle’s way and h(α) is defined via the natural extension of α.It is shown that when X is the torus and α is induced by integer matrices then ■ is zero and h(α) can be expressed via the eigenvalues of the matrices.

关键词： Entropy Heisenberg group action natural extension torus

Stereochemical editing:Catalytic racemization of secondary alcohols and amines

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Chinese Chemical Letters 2024年第5期35卷 17-31页

作者： jun zhang Zhiyao Zheng Can Zhu Department of Chemistry Fudan UniversityShanghai 200438China Department of Organic Chemistry Arrhenius LaboratoryStockholm UniversityStockholm 10691Sweden

Chiral alcohols and amines are important structural units widely existing in pharmaceuticals,agrochemicals,and food *** kinetic resolution(DKR)is an efficient strategy to deliver optically active alcohols and amines from their *** the development of DKR method,racemization catalyst plays as a crucial element with the requirement of compatibility with the kinetic resolution(KR)*** this paper,recent advance in the catalytic racemization of secondary alcohols and amines is summarized based on different types of racemizing intermediates,which are redox racemization via ketone/imine intermediates,racemization via radical intermediates,and racemization via carbocation *** racemization of secondary alcohols and amines is also enclosed.

关键词： Racemization Secondary alcohols Amines Kinetic resolution Dynamic kinetic resolution

Temperature field prediction of steel-concrete composite decks using TVFEMD-stacking ensemble algorithm

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第9期25卷 732-748页

作者： Benkun TAN da WANG Jialin SHI Lianqi zhang School of Civil Engineering Changsha University of Science&TechnologyChangsha 410114China School of Civil and Architecture Engineering Hunan University of Arts and ScienceChangde 415000China School of Civil Engineering Central South University of Forestry and TechnologyChangsha 410004China

This research aims to develop an advanced deep learning-based ensemble algorithm,utilizing environmental temperature and solar radiation as feature factors,to conduct hourly temperature field predictions for steel-concrete composite decks(SCCDs).The proposed model comprises feature parameter lag selection,two non-stationary time series decomposition methods(empirical mode decomposition(EMD)and time-varying filtering-based empirical mode decomposition(TVFEMD)),and a stacking ensemble prediction *** validate the proposed model,five machine learning(ML)models(random forest(RF),support vector regression(SVR),multilayer perceptron(MLP),gradient boosting regression(GBR),and extreme gradient boosting(XGBoost))were tested as base learners and evaluations were conducted within independent,mixed,and ensemble ***,predictions are made based on engineering *** results indicate that consideration of lag variables and modal decomposition can significantly improve the prediction performance of learners,and the stacking framework,which combines multiple learners,achieves superior prediction *** proposed method demonstrates a high degree of predictive robustness and can be applied to statistical analysis of the temperature field in *** time lag features helps account for the delayed heat dissipation phenomenon in concrete,while decomposition techniques assist in feature extraction.

关键词： Steel-concrete composite deck(SCCD) Temperature field Time-varying filtering-based empirical mode decomposition(TVFEMD) Feature selection Machine learning(ML)

Urban water system theory and its model development and application

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Science China Earth Sciences 2024年第3期67卷 704-724页

作者： jun XIA Yongyong zhang Dunxian SHE Shiyan zhang jun YANG Mingquan LV Xiang zhang Anqi LUO Shengjun WU Yang LIU Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China State Key Laboratory of Water Resources&Hydropower Engineering Sciences Wuhan UniversityWuhan 430072China Aquatic Eco Health Group Key Laboratory of Urban Environment and HealthInstitute of Urban EnvironmentFujian Key Laboratory of Watershed EcologyChinese Academy of SciencesXiamen 361021China Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China

The urban water system theory is an extension of the basin water system science on an urban scale, providing a new systematic solution for the unbalanced human-water relationship and severe water challenges, such as waterlogging, black and odorous water, and ecological degradation caused by urbanization. Most existing studies on urban water systems have focused on individual water cycle processes linked with water supply and sewage treatment plants, but mutual feedback between the water cycle and its associated material circulation and water ecology, as well as human processes, still needs further exploration. In this paper, the concept, theory, and technical methodology of the urban water system were developed based on the water cycle and basin water system science. The Urban Water System 5.0(UWS 5.0) model was developed by integrating the Time Variant Gain rainfall-runoff Model with Urban water system(TVGM_Urban) in different underlying surface conditions for analyzing the natural-social water cycle processes and their associated water environmental and ecological processes and the influence of multiscale sponge measures. Herein, five major simulation functions were realized: rainfall-runoff-nonpoint source pollutant load,water and pollutant transportations through the drainage network system, terminal regulation and purification, socioeconomic water cycle, and water system assessment and regulation. The location for the case study used in this paper was Wuhan City. The findings showed that the entire urban water system should consider the built-up area and its associated rivers and lakes as the research object and explore the integrations among the urban natural-social water cycle and river regulations inside and outside of the city as well as the effects of socioeconomic development and sponge measures on the water quantity-quality-ecology processes. The UWS 5.0 model efficiently simulated the urban rainfall-runoff process, total nitrogen(TN) and total phosphoru

关键词： Urban water system Human-water relationship Water issue Green development Theoretical basis Mathematical model

Effects of mid-passage gap with a variable surface angle on a turbine vane endwall’s aerothermal and film cooling performances

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Chinese Journal of Aeronautics 2024年第6期37卷 20-37页

作者： Zhiyu LI Kaiyuan zhang Zhigang LI jun LI Institute of Turbomachinery Xi’an Jiaotong UniversityXi’an 710049China

The mid-passage gap is an inevitable structure in a vane passage due to turbine vanes being manufactured *** coolant from this gap is able to prevent hot mainstream ingression and provide cooling protection for the endwall.A novel idea of enlarging the endwall’s coverage area and reducing the endwall’s thermal load by applying the mid-passage gap with variable surface angles is carried out in this *** endwall’s aerothermal and film cooling performances under four mid-passage gap modes at three typical mass flow ratio conditions are numerically *** indicate that under the traditional mid-passage mode,the coolant flows into the mainstream with a perpendicular incidence angle and can’t stick to the ***,cooling failure occurs,and the endwall’s thermal load is badly *** film cooling level at the suction-side endwall is improved when applying the mid-passage gap of a 45surface angle due to the secondary vortex being *** addition,when applying the mid-passage gap of a 135surface angle,the horseshoe vortex is pushed away,and the coverage area at the pressure-side endwall is enlarged *** best film cooling performance is achieved when the upstream surface angle is 135and the downstream surface angle is 45due to the adiabatic film cooling effectiveness being increased at both the pressure-and suction-side *** the mass flow ratio is 1.5%,the coverage area is enlarged by 43%,and the area-averaged adiabatic film cooling effectiveness is increased by 37%,when compared with those under the traditional mid-passage mode.

关键词： Film cooling Heat transfer Surface angle Mid-passagegap Turbinevane endwall

An artificial intelligence approach for particle transport velocity prediction in horizontal flows

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Particuology 2024年第9期92卷 234-250页

作者： Haoyu Chen Zhiguo Wang Hai Huang jun zhang College of Petroleum Engineering Xi'an Shiyou UniversityXi'an710065China Shaanxi Key Laboratory of Carbon Dioxide Sequestration and Enhanced Oil Recovery Xi'an710065China College of New Energy Xi'an Shiyou UniversityXi'an710065China Engineering Research Center of Smart Energy and Carbon Neutral in Oil&Gas Field Universities of Shaanxi ProvinceChina The Erosion/Corrosion Research Center The University of TulsaOK74104United States

Particle entrainment is an inevitable phenomenon in pipeline systems,especially during the development and extraction phases of oil and gas *** predicting the critical velocity for particle transport is a key focus for implementing effective sand control *** work presents a semi-supervised learning–deep hybrid kernel extreme learning machine(SSL-DHKELM)model for predicting the critical velocity,which integrates multiple machine learning theories including the deep learning approach,which is adept at advanced feature ***,the SSL framework enhances the model's capabilities when data availability is *** improved slime mould algorithm is also employed to optimize the model's *** proposed model has high accuracy on both the sample dataset and out-of-sample *** trained with only 10%of the data,the model's error still did not increase ***,this model achieves superior predictive accuracy compared to existing mechanistic models,demonstrating its impressive performance and robustness.

关键词： Particle transport Critical velocity Deep learning Semi-supervised learning Extreme learning machine

Memristive oscillator to memristive map,energy characteristic

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Science China(Technological Sciences) 2024年第5期67卷 1567-1578页

作者： GUO YiTong MA jun zhang XiaoFeng HU XiKui College of Electrical and Information Engineering Lanzhou University of TechnologyLanzhou730050China Department of Physics Lanzhou University of TechnologyLanzhou730050China School of Science Chongqing University of Posts and TelecommunicationsChongqing400065China

Most of nonlinear oscillators composed of capacitive and inductive variables can obtain the Hamilton energy by using the Helmholtz theorem when the models are rewritten in equivalent vector *** energy functions for biophysical neurons can be obtained by applying scale transformation on the physical field energy in their equivalent neural *** dynamical systems often have exact energy functions,while some mathematical models just suggest generic Lyapunov functions,and the energy function is effective to predict mode *** this paper,a memristive oscillator is approached by two kinds of memristor-based nonlinear circuits,and the energy functions are defined to predict the dependence of oscillatory modes on energy *** absence of capacitive variable for capacitor,the physical time t and charge q are converted into dimensionless variables by using combination of resistance and inductance(L,R),e.g.,τ=t×R/*** energy function for each memristive map is proposed by applying the similar weights as energy function for the memristive *** example,energy function for the map is obtained by replacing the variables and parameters of the memristive oscillator with corresponding variables and parameters for the memristive *** memristive map prefers to keep lower average energy than the memristive oscillator,and chaos is generated in a discrete system with two *** scheme is helpful for energy definition in maps,and it provides possible guidance for verifying the reliability of maps by considering the energy characteristic.

关键词： Hamilton energy memristor Helmholtz theorem scale transformation memristive circuit

Experimental Study of Temperature Control Based on Composite Phase Change Materials during Charging and Discharging of Battery

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Journal of Thermal Science 2024年第2期33卷 578-590页

作者： LI Xiaolin WANG jun CAO Wenxiang zhang Xuesong School of Automotive and Traffic Engineering Jiangsu UniversityZhenjiang212013China

This study is to utilize the heat-absorbing and releasing capabilities of phase change materials(PCM)to regulate the surface temperature fluctuations of batteries during charging and *** goal is to keep the battery within the optimal operating temperature *** impact of PCM thickness and phase change temperature on battery temperature is investigated by encircling a cylindrical battery with a PCM *** improve the thermal conductivity of PCM,expanded graphite(EG) is added to make a composite phase change material(CPCM),and the effects of various EG mass ratios on battery surface temperature and CPCM utilization level are *** findings indicate that increasing PCM thickness effectively extends temperature control time,but its impact is *** difference in phase change temperature of PCM controls the battery temperature in different temperature *** phase change temperatures are unsuitable for controlling battery temperature in high temperature *** addition of EG enhances the thermal conductivity of PCM,leading to further control of battery *** results show that the addition of 6%(mass ratio) EG to CPCM extends the effective temperature control time by 11 min and improves by 28% compared to a single *** CPCM utilization is also more satisfactory and achieved a balance between heat storage and thermal conductivity in a battery thermal management system(BTMS) based on PCM.

关键词： phase change material expanded graphite thermal management system effective control time

Impact response and energy absorption of metallic buffer with entangled wire mesh damper

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Defence Technology（防务技术） 2024年第5期35卷 137-150页

作者： Chao Zheng jun Wu Mangong zhang Xin Xue Institute of Metal Rubber&Vibration Noise School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou 350116China Wuhan Second Ship Design and Research Institute Wuhan 430205China

An innovative metallic buffer consisting of series-connected hat-shaped entangled wire mesh damper(EWMD)and parallel springs are proposed in this work to enhance the reliability of engineering *** impact response and the energy dissipation mechanism of hat-shaped EWMD under different quasi-static compression deformations(2-7 mm)and impact heights(100-200 mm)are investigated using experimental and numerical *** results demonstrate distinct stages in the quasi-static mechanical characteristics of hat-shaped EWMD,including stiffness softening,negative stiffness,and stiffness *** loss factor gradually increases with increasing compression deformation before entering the stiffness hardening *** impact loads,the hat-shaped EWMD exhibits optimal impact energy absorption when it enters the negative stiffness stage(150 mm),resulting in the best impact isolation effect of metallic ***,the impact energy absorption significantly decreases when hat-shaped EWMD enters the stiffness hardening ***,quasi-static compression analysis after experiencing different impact loads reveals the disappearance of the negative stiffness ***,with increasing impact loads,the stiffness hardening point progressively shifts to an earlier stage.

关键词： Metallic buffer Hat-shaped EWMD Drop impact Energy absorption characteristics Mechanical behavior