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Journal of Thermal Science 2024年第2期33卷 675-695页

作者： ZHANG Hao ZHAO Hongxia ZHANG Xiuao zeng hongxuan DENG Jianqiang School of Energy and Power Engineering Shandong UniversityJi’nan250061China School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an710049China

The steam ejector is a crucial component in the waste heat recovery *** performance determines the amount of recovered heat and system ***,poor ejector performance has always been the main bottleneck for system ***,this study proposes an optimization methodology to improve the steam ejector's performance by utilizing computational fluid dynamics(CFD) techniques,response surface methodology(RSM),and genetic algorithm(GA).Firstly,a homogeneous equilibrium model(HEM) was established to simulate the two-phase flow in the steam ***,the orthogonal test was presented to the screening of the key decision variables that have a significant impact on the entrainment ratio(ER).Next,the RSM was used to fit a response surface regression model(RSRM).Meanwhile,the effect of the interaction of geometric parameters on the performance of the steam ejector was ***,GA was employed to solve the RSRM's global optimal ER *** results show that the RSRM exhibits a good fit for ER(R^(2)=0.997).After RSM and GA optimization,the maximum ejector efficiency is 27.94%,which is 48.38% higher than the initial ejector of 18.83%.Furthermore,the optimized ejector efficiency is increased by 46.4% on average under off-design ***,the results reveal that the combination of CFD,RSM,and GA presents excellent reliability and feasibility in the optimization design of a two-phase steam ejector.

关键词： two-phase steam ejector optimization methodology CFD techniques response surface methodology genetic algorithm homogeneous equilibrium model

跨临界CO_(2)两相流可调式喷射器的流动模拟和性能分析

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化工学报 2023年第11期74卷 4515-4526页

作者：陈壮刘光弟曾宏轩赵红霞山东大学能源与动力工程学院山东济南250061 西安交通大学能源与动力工程学院陕西西安710049

作为CO_(2)制冷/热泵系统重要的节能部件,喷射器的工作能力对系统性能的提升有着重要影响。尽管CO_(2)喷射器的结构简单,但其内部流动十分复杂,包含非平衡相变、跨声速和马赫波等物理现象。为此,本研究建立了用于CO_(2)两相流模拟的均... 详细信息

作为CO_(2)制冷/热泵系统重要的节能部件,喷射器的工作能力对系统性能的提升有着重要影响。尽管CO_(2)喷射器的结构简单,但其内部流动十分复杂,包含非平衡相变、跨声速和马赫波等物理现象。为此,本研究建立了用于CO_(2)两相流模拟的均相弛豫模型(HRM),通过实验数据验证了模型的可靠性,并以此开展了对可调式喷射器的数值研究,分析了有无探针、探针位置和工况变化对可调式喷射器性能和内部流动的影响。研究结果表明,探针增加了一次流的不可逆损失,同时也改变了喷嘴出口一次流的膨胀状态;通过探针调整喷嘴喉部面积,提高了喷射器适应不同工况运行的能力,使喷射器在不同工况下保持最佳的运行状态;与固定式喷射器相比,可调式喷射器效率平均提升10.74%。

关键词：可调式喷射器 CO_(2) 均相弛豫模型两相流计算流体力学

Comparative Study on Different Methods for Prediction of Thermal Insulation Performance of Thermal Barrier Coating Used on Turbine Blades

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Journal of Thermal Science 2024年第1期33卷 172-189页

作者： ZHANG Zhixin zeng Wu ZHANG Xiaodong zeng Yuntao Advanced Gas Turbine Laboratory Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China Key Laboratory of Advanced Energy and Power Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China Innovation Academy for Light-duty Gas Turbine Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

As turbine inlet temperature gets higher and higher,thermal barrier coating(TBC) is more and more widely used in turbine *** turbine blades with TBC,it is of great significance to evaluate the temperature distribution of its substrate metal quickly and accurately,especially during the design *** different degrees of simplification such as whether to consider the change of the geometric size of the fluid domain by TBC and whether to consider the planar heat conduction in TBC,three different methods used in conjugate heat transfer(CHT) simulation to model the TBC of the turbine blades have been developed and widely used by ***,little research has been conducted to investigate the influence of the three methods on the temperature distribution of turbine *** fill this gap,three geometric models were *** are a solid conduction model with a substrate metal layer and a TBC layer,a transonic turbine vane with internal cooling and TBC,and a plate cylindrical film hole cooling model with *** methods were used in these geometric models and their differences were carefully analyzed and *** result shows that for the conduction model used in this paper,with the same TBC surface temperature distribution,the difference between the three methods is very small and can be *** a transonic turbine vane with internal cooling,regarding the local maximum temperature of the substrate-TBC interface,the largest difference between the method in which TBC is considered as a thermal resistance or a virtual layer of cells and the method in which three-dimensional heat conduction equation of TBC is solved occurs at the trailing *** difference near the leading edge is below *** employed to the film cooling model,the difference of the laterally averaged temperature of the substrate-TBC interface can be 8 K which is mainly due to the change of the length to diameter ratio of the film cooling hole by *** the substrate

关键词： turbine blade thermal barrier coating conjugate heat transfer film cooling hole

Nested Saturated Control of Uncertain Complex Cascade Systems Using Mixed Saturation Levels

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1163-1174页

作者： Meng Li Zhigang zeng Wuhan National Laboratory for Optoelectronics Wuhan 430074 School of Artificial Intelligence and Automation Huazhong University of Science and TechnologyWuhan 430074China School of Artificial Intelligence and Automation Huazhong University of Science and TechnologyWuhan 430074 Key Laboratory of Image Processing and Intelligent Control of Education Ministry of China Wuhan 430074China

This study addresses the problem of global asymptotic stability for uncertain complex cascade systems composed of multiple integrator systems and non-strict feedforward nonlinear systems. To tackle the complexity inherent in such structures, a novel nested saturated control design is proposed that incorporates both constant saturation levels and state-dependent saturation levels. Specifically, a modified differentiable saturation function is proposed to facilitate the saturation reduction analysis of the uncertain complex cascade systems under the presence of mixed saturation levels. In addition, the design of modified differentiable saturation function will help to construct a hierarchical global convergence strategy to improve the robustness of control design scheme. Through calculation of relevant inequalities, time derivative of boundary surface and simple Lyapunov function,saturation reduction analysis and convergence analysis are carried out, and then a set of explicit parameter conditions are provided to ensure global asymptotic stability in the closed-loop systems. Finally, a simplified system of the mechanical model is presented to validate the effectiveness of the proposed method.

关键词： method saturation differentiable

Aggregation-regulated bioreduction process of graphene oxide by Shewanella bacteria

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Chinese Journal of Chemical Engineering 2024年第5期69卷 56-62页

作者： Kaixin Han Yibo zeng Yinghua Lu Ping zeng Liang Shen Department of Chemical and Biochemical Engineering College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Pen-Tung Sah Institute of Micro-Nano Science and Technology Xiamen UniversityXiamen 361005China Chinese Research Academy of Environmental Sciences Beijing 100012China

The bioreduction of graphene oxide(GO)using environmentally functional bacteria such as Shewanella represents a green approach to produce reduced graphene oxide(rGO).This process differs from the chemical reduction that involves instantaneous molecular *** bioreduction,the contact of bacterial cells and GO is considered the rate-limiting *** reveal how the bacteria-GO integration regulates rGO production,the comparative experiments of GO and three Shewanella strains were carried ***-transform infrared spectroscopy,X-ray photoelectron spectroscopy,Raman spectroscopy,and atomic force microscopy were used to characterize the reduction degree and the aggregation *** results showed that a spontaneous aggregation of GO and Shewanella into the condensed entity occurred within 36 h.A positive linear correlation was established,linking three indexes of the aggregation potential,the bacterial reduction ability,and the reduction degree(ID/IG)comprehensively.

关键词： Graphene oxide Reduced graphene oxide Bioreduction Aggregation Shewanella

Eigenvalues for the Clamped Plate Problem of L_(ν)^(2) Operator on Complete Riemannian Manifolds

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Acta Mathematica Sinica,English Series 2024年第9期40卷 2223-2243页

作者： Ling Zhong zeng Jiangxi Provincial Center for Applied Mathematics&School of Mathematics and Statistics Jiangxi Normal UniversityNanchang 330022P.R.China

L_(ν)operator is an important extrinsic differential operator of divergence type and has profound geometric *** this paper,we consider the clamped plate problem of L2νoperator on a bounded domain of the complete Riemannian manifolds.A general formula of eigenvalues of L_(ν)^(2)operator is *** this general formula,we obtain some estimates for the eigenvalues with higher order on the complete Riemannian *** several fascinating applications,we discuss this eigenvalue problem on the complete translating solitons,minimal submanifolds on the Euclidean space,submanifolds on the unit sphere and projective *** particular,we get a universal inequality with respect to the L_(II) operator on the translating ***,it is very difficult to get universal inequalities for weighted Laplacian and even Laplacian on the complete Riemannian ***,this work can be viewed as a new contribution to universal estimate.

关键词： Mean curvature flows L_(ν)^(2)operator clamped plate problem eigenvalues Riemannian manifolds translating solitons

Cluster analysis reveals a homogeneous subgroup of PCOS women with metabolic disturbance associated with adverse reproductive outcomes

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Chinese Medical Journal 2024年第5期137卷 604-612页

作者： Hanxiao Chen Rujun zeng Xun zeng Lang Qin The Reproductive Medical Center Department of Obstetrics and GynecologyWest China Second University HospitalSichuan UniversityChengduSichuan 610041China Key Laboratory of Birth Defects and Related of Women and Children of Ministry of Education West China Second University HospitalSichuan UniversityChengduSichuan 610041China

Background:Polycystic ovarian syndrome(PCOS)is a heterogeneous and complex reproductive endocrinological disease that could lead to *** were many attempts to classify PCOS but it remains unclear whether there is a specific subgroup of PCOS that is associated with the best or worst reproductive outcomes of assisted reproductive techniques(ART).Methods:Infertile PCOS patients who underwent their first cycle of in vitro fertilization(IVF)in West China Second University Hospital,Sichuan University from January 2019 to December 2021 were *** clinical and laboratory information of each individual were *** cluster analysis was *** ovarian stimulation parameters and reproductive outcomes were collected and compared between the different clusters of ***:Our analysis clustered women with PCOS into"reproductive","metabolic",and"balanced"clusters based on nine *** group was characterized by high levels of testosterone(T),sex hormone-binding globulin(SHBG),follicular stimulation hormone(FSH),luteinizing hormone(LH),and anti-Müllerian hormone(AMH).Metabolic group was characterized by high levels of body mass index(BMI),fasting insulin,and fasting *** group was characterized by low levels of the aforementioned reproductive and metabolic parameters,except for *** with PCOS patients in reproductive and balanced clusters,those in metabolic cluster had lower rates of good quality day 3 embryo and blastocyst ***,PCOS patients in the reproductive cluster had greater fresh embryo transfer(ET)cancelation rate and clinical pregnancy rate after fresh ET than metabolic cluster(odds ratio[OR]=3.37,95%confidence interval[CI]:1.77-6.44,and OR=6.19,95%CI:1.58-24.24,respectively).And compared with PCOS of metabolic cluster,PCOS of balanced cluster also had higher chance for fresh ET cancelation(OR=2.83,95%CI:1.26-6.35).Conclusion:Our study suggested that PCOS patients in met

关键词： Polycystic ovarian syndrome Assisted reproductive techniques Clustering analysis Metabolic disturbance Clinical pregnancy

Analysis of gravity wave activity during stratospheric sudden warmings in the northern hemisphere

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Earth and Planetary Physics 2024年第2期8卷 415-422页

作者： XuanYun zeng Guang Zhong School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410000China Key Laboratory of Geospace Environment Chinese Academy of SciencesUniversity of Science&Technology of ChinaHefei 230026China

Due to the significant changes they bring to high latitude stratospheric temperature and wind,stratospheric sudden warmings(SSWs)can have an impact on the propagation and energy distribution of gravity waves(GWs).The variation characteristics of GWs during SSWs have always been an important *** temperature data from January to March in 2014−2016,provided by the Constellation Observing System for Meteorology,Ionosphere and Climate(COSMIC)mission,we have analyzed global GW activity at 15−40 km in the Northern Hemisphere during SSW *** the SSWs that we studied,the stratospheric temperature rose in one or two longitudinal regions in the Northern Hemisphere;the areas affected extended to the east of 90°*** these SSWs,the potential energy density(E_(p)of GWs expanded and covered a larger range of longitude and altitude,exhibiting an eastward and downward *** E_(p)usually increased,while partially filtered by the eastward zonal *** zonal winds weakened or turned westward,E_(p)began to *** SSWs,the E_(p)usually *** observations can serve as a reference for analyzing the interaction mechanism between SSWs and GWs in future work.

关键词： stratospheric sudden warming gravity wave wind filter

Two-dimensional localized modes in nonlinear systems with linear nonlocality and moiré lattices

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Frontiers of physics 2024年第4期19卷 265-273页

作者： Xiuye Liu Jianhua zeng Center for Attosecond Science and Technology State Key Laboratory of Transient Optics and PhotonicsXi’an Institute of Optics and Precision Mechanics of Chinese Academy of SciencesXi’an 710119China University of Chinese Academy of Sciences Beijing 100049China Collaborative lnnovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Periodic structures structured as photonic crystals and optical lattices are fascinating for nonlinear waves engineering in the optics and ultracold atoms ***éphotonic and optical lattices—two-dimensional twisted patterns lie somewhere in between perfect periodic structures and aperiodic ones—are a new emerging investigative tool for studying nonlinear localized waves of diverse ***,a theory of two-dimensional spatial localization in nonlinear periodic systems with fractional-order diffraction(linear nonlocality)and moiréoptical lattices is ***,the flat-band feature is well preserved in shallow moiréoptical lattices which,interact with the defocusing nonlinearity of the media,can support fundamental gap solitons,bound states composed of several fundamental solitons,and topological states(gap vortices)with vortex charge s=1 and 2,all populated inside the finite gaps of the linear Bloch-wave *** the linear-stability analysis and direct perturbed simulations,the stability and instability properties of all the localized gap modes are surveyed,highlighting a wide stability region within the first gap and a limited one(to the central part)for the third *** findings enable insightful studies of highly localized gap modes in linear nonlocality(fractional)physical systems with shallow moirépatterns that exhibit extremely flat bands.

关键词： moiréoptical lattices gap solitons and vortices ultracold atoms Gross-Pitaevskii/nonlinear fractional Schrödinger equation nonlinear fractional systems

Equivariant Chern Classes of Orientable Toric Origami Manifolds

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Chinese Annals of Mathematics,Series B 2024年第2期45卷 221-234页

作者： Yueshan XIONG Haozhi zeng School of Mathematics and StatisticsHuazhong University of Science and Technology Wuhan 430074China

A toric origami manifold,introduced by Cannas da Silva,Guillemin and Pires,is a generalization of a toric symplectic *** a toric symplectic manifold,its equivariant Chern classes can be described in terms of the corresponding Delzant polytope and the stabilization of its tangent bundle splits as a direct sum of complex line *** in general a toric origami manifold is not simply connected,so the algebraic topology of a toric origami manifold is more difficult than a toric symplectic *** this paper they give an explicit formula of the equivariant Chern classes of an oriented toric origami manifold in terms of the corresponding origami ***,they prove the stabilization of the tangent bundle of an oriented toric origami manifold also splits as a direct sum of complex line bundles.

关键词： Equivariant Chern classes Toric origami manifolds Unitary structures Spin structures