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Numerical Simulation of Radiation Transport to Improve Microalgae Cultivation in an Air-Lift Photobioreactor

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Journal of Thermal Science 2025年第1期34卷 62-76页

作者： ZHANG Xianbin LI Mingjia HUNG Tzuchen ZHANG Zixun Key laboratory of Thermo-fluid Science and engineering of Ministry of Education School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China School of Mechanical engineering Beijing Institute of TechnologyBeijing 100081China Department of Mechanical engineering Taipei University of TechnologyTaipei 106344China

A comprehensive numerical model is developed to simulate the growth of microalgae under light/dark cycling *** purpose of this study is to predict the growth rate of Chlorella vulgaris cultivated in photobioreactors(PBRs)in order to improve the light conditions for microalgae and enhance the photosynthetic *** fluid dynamics(CFD)is used to simulate its internal hydrodynamic *** Lagrangian method is employed to track the movement of microalgae *** radiative transfer equation(RTE)is used to obtain light intensity *** combination of light radiation field and microalgae cell motions is used to construct the light history and they are integrated into the model of the photosynthetic units(PSU)to calculate the microalgae growth *** numerical results demonstrate that enhanced light/dark cycling frequency with ordered mixing can promote efficient microalgae *** effect of the vortex flow field generated by the baffles in an air-lift PBR is analyzed for increasing microalgae growth *** using the 1:1 baffle spacing,the biomass production of microalgae is increased by 41.8% compared to the original PBR.

关键词： photobioreactor light distribution particle tracking structure optimization

A Wind Tunnel Experimental Study on the Wake Characteristics of a Horizontal Axis Wind Turbine

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Journal of Thermal Science 2025年第1期34卷 145-158页

作者： GUO Xingduo LI Yinran LI Rennian MA Yulong WEI Kui College of Energy and Power engineering Lanzhou University of TechnologyLanzhou 730050China Key laboratory of fluid Machinery and Systems Lanzhou 730050China Gansu Provincial Technology Centre for Wind Turbines Lanzhou 730050China

The characteristics of wind turbine wakes are influenced by multiple factors,including the atmospheric boundary layer(ABL)wind and wind turbine operating conditions(e.g.,tip speed ratio and yaw angle).In this study,two types of ABL winds with different velocity gradients and turbulence intensities are generated in a wind tunnel through configurations of spires,baffles,and various numbers of roughness elements.A wind turbine with a rotor diameter of 0.8 m and a hub height of 0.6 m is tested under varying tip speed ratios,yaw angles,and ABL wind *** results indicate that the streamwise velocity deficit in the near-wake region becomes more pronounced with an increase in the tip speed ratio,while the far-wake velocity deficit remains largely unaffected by changes in the tip speed *** the yaw angle increases,the wake deflection becomes more prominent and the wake narrows;the offset of the wake center at various downstream positions grows linearly,reaching a maximum value of approximately half the rotor ***,the turbulence level and influence range in the wake region are reduced when the turbine is *** ABL wind conditions,high turbulence intensity in the incoming flow accelerates wake recovery,and the Reynolds stress at different lateral positions tends to become consistent with increasing longitudinal ***,turbulence has a significant impact on the meandering characteristics of the wind turbine wake,with greater fluctuations in the wake center observed under higher turbulence ***,this study provides insights that could inform the optimal operation of wind farms.

关键词： horizontal axis wind turbine wind tunnel experiment wind turbine wake turbulence

As-cast Ti_(x)(AlVCr)_(100−x)light-weight medium entropy alloys with high strength and uniform compressive plasticity

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Transactions of Nonferrous Metals Society of China 2025年第1期35卷 194-206页

作者： Ming-jie KAI Yu-jie MA Xiao-tian WANG Liang CHENG Jian-bo HU Yao-yao HU Tai-ran XU Gui-jiang LI Xiang-kang MENG Zhen-hua CAO College of Materials Science and engineering Nanjing Tech UniversityNanjing 210009China School of Intelligent Manufacturing and Information Jiangsu Shipping CollegeNantong 226010China laboratory for Shock Wave and Detonation Physics Institute of Fluid PhysicsChina Academy of Engineering PhysicsMianyang 621900China National laboratory of Solid State Microstructures College of Engineering and Applied SciencesNanjing UniversityNanjing 210093China

The effect of Ti content on the microstructure and mechanical properties of as-cast light-weight Ti_(x)(AlVCr)_(100−x)medium entropy alloys was studied by compressive tests,X-ray diffraction,scanning electron microscopy and transmission electron *** results suggest that yield strength increases and then decreases with the increment of Ti *** Ti_(60)(AlVCr)_(40)alloy has the best combination of high strength of 1204 MPa and uniform plastic strain of 70%,possessing a high specific yield strength of 255 MPa·cm^(3)/*** enhancement of strength is mainly attributed to the synergic effects of solid-solution and coherent nano-precipitation strengthening,while dislocation motion such as dislocation pinning,entanglement and dislocation cells significantly increases the strain-hardening capacity.

关键词： TiAlVCr medium entropy alloy solid solution strengthening b2 precipitate strain hardening behavior

Synthesis ofδ-MnO_(2)via ozonation routine for low temperature formaldehyde removal

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Journal of Environmental Sciences 2025年第1期147卷 642-651页

作者： Guijun Fan Yacong Guo Shaohua Chai Le Zhang Jian Guan Guojun Ma Ning Han Yunfa Chen State Key laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China College of Chemical engineering University of Chinese Academy of SciencesBeijing 100049China Key laboratory of Science and Technology on Particle Materials Institute of Process EngineeringChinese Academy of SciencesBeijing 361021China Key laboratory for Mechanics in fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Petrochemical engineering&Environment Zhejiang Ocean UniversityZhoushan 316022China

Nowadays,it is still a challenge to prepared high efficiency and low cost formaldehyde(HCHO)removal catalysts in order to tackle the long-living indoor air ***,δ-MnO_(2)is successfully synthesized by a facile ozonation strategy,where Mn^(2+)is oxidized by ozone(O_(3))bubble in an alkaline *** presents one of the best catalytic properties with a low 100%conversion temperature of 85℃for 50 ppm of HCHO under a GHSV of 48,000 mL/(g·hr).As a comparison,more than 6 times far longer oxidation time is needed if O3 is replaced by O_(2).Characterizations show that ozonation process generates a different intermediate of tetragonalβ-HMnO_(2),which would favor the quick transformation into the final productδ-MnO_(2),as compared with the relatively more thermodynamically stable monoclinicγ-HMnO_(2)in the O_(2)***,HCHO is found to be decomposed into CO_(2)via formate,dioxymethylene and carbonate species as identified by room temperature insitu diffuse reflectance infrared fourier transform *** these results show great potency of this facile ozonation routine for the highly activeδ-MnO_(2)synthesis in order to remove the HCHO contamination.

关键词： δ-MnO_(2) Ozone oxidation HCHO oxidation In-situ DRIFTS

Oxidative degradation and upcycling of polyethylene wastes

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Science China Chemistry 2025年第2期68卷 430-443页

作者： Yizhen Che Yanfen Wu Zhiqiang Niu State Key laboratory of Chemical engineering Department of Chemical EngineeringTsinghua UniversityBeijing 100084China Ordos laboratory Ordos 017010China

Plastics have become omnipresent in modern life due to their versatility and ***,this convenience comes at the cost of substantial waste *** inherent chemical stability of plastics complicates its recycling,leading to environmental pollution and ecological *** mini-review highlights recent advancements in addressing this challenge by oxidative transformation of polyethylene(PE)into new functional polymers,value-added chemicals,and carbon-based *** first discuss the introduction of hydroxyl,carbonyl groups onto PE with a focus on the functionalization degree and ***,approaches for PE oxidation into dicarboxylic acids and short-chain oxidized PE are described and compared,with an emphasis on the tandem reactions for converting mixed dicarboxylic acids into other value-added *** also briefly discuss the oxidative transformation of PE into carbon-based materials and summarize the progress in qualitative and quantitative analysis of oxidation ***,we conclude this mini-review by highlighting the challenges and opportunities in the field.

关键词： oxidation polyethylene upcycling chemical conversion plastics

Automatic and Rapid Throughflow-Based Optimal Design Method for Multi-Stage Axial-Flow Compressors

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Journal of Thermal Science 2025年第1期34卷 77-91页

作者： LEI Fan ZHANG Xiawen JU Yaping ZHANG Chuhua Department of fluid Machinery and engineering School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China State Key laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong UniversityXi'an 710049China Production and Environmental Department China Huaneng Group.Co.Ltd.Beijing 100031China

Throughflow design has the advantages of less time consumption and large optimization space,and thus is the corner stone of advanced design system of multi-stage axial-flow *** majority of relevant studies were limited to the throughflow inverse designs,and quite few works have been till now devoted to the throughflow optimal *** this work,an automatic and rapid throughflow-based optimal design method is proposed for axial-flow compressors in which a throughflow inverse design solver is embedded in optimal genetic algorithm to improve the design efficiency of axial-flow *** types of design parameters in the throughflow inverse design of axial-flow compressors,i.e.,swirl and shroud curve,are simultaneously used to optimize both the blade shape and flow *** proposed method is validated by the redesign optimization of the benchmark axial-flow compressor NASA Stage 35,and the CFD predictions show that the throughflow-based optimization leads to 1.18% efficiency benefit at design *** proposed method is then utilized to the two-dimensional throughflow optimal design of a large-scale 6.5-stage axial-flow industrial *** optimal design results are confirmed by CFD predictions,indicating that the proposed method can effectively improve the design adiabatic efficiency of the compressors by 1.09% within a few minutes on desk-top *** throughflow design implications are also obtained for advanced axial-flow industrial *** work could enhance the capability of throughflow design method and has engineering application value to explore the throughflow optimization space of multi-stage axial-flow compressors.

关键词： multi-stage axial-flow compressor throughflow design empirical correlations genetic algorithm aerodynamic optimization

Rock fracture mechanism of buffer blasting with cushion layer at the borehole bottom

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 325-334页

作者： Xinguang Zhu Chenxi Ding Zhe Sui Hong Su Xu Guo School of Civil and Resources engineering University of Science and Technology BeijingBeijing 100083China Key laboratory for Mechanics in fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Mechanics and Civil engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Chemical and Blasting engineering Anhui University of Science and TechnologyHuainan 232001China

This study primarily investigates the rock fracture mechanism of bottom cushion layer blasting and explores the effects of the bottom cushion layer on rock *** involves analyses of the evolution patterns of blasting stress,characteristics of crack distribution,and rock fracture features in the ***,blasting model experiments were carried out using the dynamic caustics principle to investigate the influence of bottom cushion layers and initiation methods on the integrity of the bottom rock *** experimental results indicate that the combined use of bottom cushion layers and inverse initiation effectively protects the integrity of the bottom rock ***,the process of stress wave propagation and dynamic crack propagation in rocks was simulated using the continuum-discontinuum element method(CDEM)and the Landau explosion source model,with varying thicknesses of bottom cushion *** numerical simulation results indicate that with increasing cushion thickness,the absorption of energy generated by the explosion becomes more pronounced,resulting in fewer cracks in the bottom rock *** illustrates the positive role of the cushion layer in protecting the integrity of the bottom rock mass.

关键词： bottom cushion layer blasting crack propagation continuum-discontinuum element method dynamic stress intensity factor

A regularization method for delivering the fourth-order derivative of experimental data and its applications in fluid-structure interactions

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Science China Technological Sciences 2025年第3期68卷 363-380页

作者： Fan DUAN Jin-Jun WANG fluid Mechanics Key laboratory of Education Ministry Beijing University of Aeronautics and Astronautics

In the experimental investigation of fluid-structure interactions regarding the undulatory motion like flag flapping or fish swimming, solving the force distribution on the flexible body stands as an indispensable endeavor to gain insights into the underlying dynamic mechanisms. However, the solving process entails high-order numerical derivatives of experimental data, which poses a formidable challenge for experimental studies on fluid-structure interactions, given that the measurement noise inherent in experimental data renders the problem ill-posed. The commonly practiced regularization methods for numerical derivatives are feeble to tackle the fourth-order derivative associated with the bending force; those methods, in particular, require predetermined parameters about the unknown noise. We introduce here an empirical regularization method founded upon the kernel-term modification in the frequency domain, notably capable of determining the fourth derivative of experimental *** leveraging the potentials of the iterative operations, our method enables the reliable estimation of an approximately optimal regularization parameter, all without reliance on any a priori knowledge about the noise characteristics. To demonstrate the reliability, robustness, and accuracy of the method, we perform rigorous numerical assessments using different data models that are infused with noise varying several orders of magnitude. Additionally, practical application of this method is achieved in the experiment on a flexible film flapping in the gusty flow, where the spatiotemporal distribution of the bending force density on the film is calculated by integrating this method with a linear reconstruction.

关键词： high-order numerical derivative regularization film fluid-structure interactions bending force

Sulfur doping and oxygen vacancy in In2O3 nanotube co-regulate intermediates of CO2 electroreduction for efficient HCOOH production and rechargeable Zn-CO2 battery

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Journal of Energy Chemistry 2025年第2期101卷 474-484页

作者： Yu Li Zhengrong Xu Quanxin Guo Qin Li Rui Liu Key laboratory of Advanced Civil engineering Materials of Ministry of Education School of Materials Science and Engineering Tongji University

By manipulating the distribution of surface electrons,defect engineering enables effective control over the adsorption energy between adsorbates and active sites in the CO2reduction reaction（CO2RR）.Herein,we report a hollow indium oxide nanotube containing both oxygen vacancy and sulfur doping（V_o-Sx-In2O3） for improved CO2-to-HCOOH electroreduction and *** componential synergy significantly reduces the*OCHO formation barrier to expedite protonation process and creates a favorable electronic micro-environment for*HCOOH *** a result,the CO2RR performance of Vo-Sx-In2O3outperforms Pure-In2O3and V_o-In2O3,where V_o-S53-In2O3exhibits a maximal HCOOH Faradaic efficiency of 92.4% at-1,2 V *** hydrogen electrode（RHE） in H-cell and above 92%over a wide window potential with high current density(119.1 mA cm-2at-1.1 V ***) in flow ***,the rechargeable Zn-CO2battery utilizing V_o-S53-In2O3as cathode shows a high power density of 2.29 mW cm-2and a long-term stability during charge-discharge *** work provides a valuable perspective to elucidate co-defective catalysts in regulating the intermediates for efficient CO2RR.

关键词： CO2 electroreduction In2O3 Intermediate Oxygen vacancy Sulfur doping Zn-CO2 battery