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Numerical simulation on directional solidification and heat treatment processes of turbine blades

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China Foundry 2024年第5期21卷 476-490页

作者： ye-yuan Hu Ju-huai Ma Qing-yan Xu School of Materials Science and Engineering Tsinghua UniversityKey Laboratory for Advanced Materials Processing TechnologyMinistry of EducationBeijing 100084China

Study on turbine blades is crucial due to their critical role in ensuring the efficient and reliable operation of aircraft ***-based single crystal superalloys are extensively used in the hot manufacturing of turbine blades due to their exceptional high-temperature mechanical *** hot manufacturing of single crystal blades involves directional solidification and heat *** manufacturing of these blades is time-consuming,capital-intensive,and often insufficient to meet industrial *** simulation techniques have gained widespread acceptance in blade manufacturing research due to their low energy consumption,high efficiency,and rapid turnaround *** article introduces the modeling and simulation of hot manufacturing in single crystal *** discussion outlines the prevalent mathematical models employed in numerical simulations related to blade hot *** encapsulates the advancements in research concerning macro to micro-level numerical simulation techniques for directional solidification and heat treatment ***,potential future trajectories for the numerical simulation of single crystal blade hot manufacturing are also discussed.

关键词： single crystal blades Ni-based superalloy directional solidification heat treatment numerical simulation

Multiscale Characteristics and Connection Mechanisms of Attraction Networks:A Trajectory Data Mining Approach Leveraging Geotagged Data

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Chinese Geographical Science 2024年第3期34卷 533-547页

作者： JIANG Hongqiang WEI ye MEI Lin WANG Zhaobo School of Resource and Environment Engineering Ludong UniversityYantai 264025China School of Geographical Sciences Northeast Normal UniversityChangchun 130024China Changchun University of Finance and Economics Changchun 130122China Jilin Jizhi City Architectural Design Co. LTDChangchun 130012China

Urban tourism is considered a complex system,and multiscale exploration of the organizational patterns of attraction networks has become a topical issue in urban tourism,so exploring the multiscale characteristics and connection mechanisms of attraction networks is important for understanding the linkages between attractions and even the future destination *** paper uses geotagging data to compare the links between attractions in Beijing,China during four different periods:the pre-Olympic period(2004–2007),the Olympic Games and subsequent‘heat period’(2008–2013),the post-Olympic period(2014–2019),and the COVID-19(Corona Virus Disease 2019)pandemic period(2020–2021).The aim is to better understand the evolution and patterns of attraction networks at different scales in Beijing and to provide insights for tourism planning in the *** results show that the macro,meso-,and microscales network characteristics of attraction networks have inherent logical relationships that can explain the commonalities and differences in the development process of tourism *** macroscale attraction network degree Matthew effect is significant in the four different periods and exhibits a morphological monocentric structure,suggesting that new entrants are more likely to be associated with attractions that already have high *** mesoscale links attractions according to the common purpose of tourists,and the results of the community segmentation of the attraction networks in the four different periods suggest that the functional polycentric structure describes their clustering effect,and the weak links between clusters result from attractions bound by incomplete information and distance,and the functional polycentric structure with a generally more efficient network of *** pattern structure at the microscale reveals the topological transformation relationship of the regional collaboration pattern,and the attraction network structure in the four diff

关键词： attraction network travel mobility polycentric structure network motif connectivity mechanism destination management organization(DMO) destination planning Beijing,China

Clinical observation on 90 cases of primary dysmenorrhea treated by buccal acupuncture therapy:a randomized controlled study

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Journal of Traditional Chinese Medicine 2024年第1期44卷 172-181页

作者： YANG Yi ye Huijun ZHENG Huiling JIN Lihua Department of Obstetrics and Gynecology the Second Affiliated Hospital of Zhejiang Chinese Medical UniversityXinhua Hospital of Zhejiang ProvinceHangzhou 310005China

OBJECTIVE:To explore the short-term and long-term efficacy of buccal acupuncture therapy in the treatment of patients with primary dysmenorrhea(PD).METHODS:A total of 90 patients with PD who were admitted to the Second Affiliated Hospital of Zhejiang University of Traditional Chinese Medicine from January 2020 to December 2021 were included in this study and randomly divided into three groups,including the observation group,the control group,and the placebo group,with 30 patients in each *** in the observation group were treated according to the syndrome types of Traditional Chinese Medicine,those in the control group were treated with Saridon,and those in the placebo group received a *** visual analog scale(VAS)scores of these patients were evaluated at different time points(before treatment,5 min after needle retention,30 min after needle retention,1 h after treatment,2 h after treatment,1 d after treatment,and 2 d after treatment).The Cox Menstrual Symptom Scale(CMSS)scores were assessed before the treatment and after three courses of ***,these two scales were also evaluated during ***,the pain score and adverse reactions of these patients were assessed during ***:After treatment,the VAS and CMSS scores in the observation group decreased significantly(P<0.05)5 and 30 min after needle retention and after ***:Buccal acupuncture therapy is verified to have short-term efficacy in the treatment of *** addition,this therapy has an immediate analgesic effect and long-term efficacy in reducing the severity and frequency of PD.

关键词： buccal acupuncture therapy primary dysmenorrhea pain score randomized controlled trial

Co/CoO heterojunction rich in oxygen vacancies introduced by O2 plasma embedded in mesoporous walls of carbon nanoboxes covered with carbon nanotubes for rechargeable zinc-air battery

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Carbon Energy 2024年第7期6卷 14-25页

作者： Leijun ye Weiheng Chen Zhong-Jie Jiang Zhongqing Jiang Key Laboratory of Optical Field Manipulation of Zhejiang Province Department of PhysicsZhejiang Sci-Tech UniversityHangzhouChina Department of Mechanical Engineering Ningbo University of TechnologyNingboChina Guangzhou Key Laboratory for Surface Chemistry of Energy Materials Guangdong Engineering and Technology Research Center for Surface Chemistry of Energy MaterialsCollege of Environment and EnergySouth China University of TechnologyGuangzhouChina

Herein,Co/CoO heterojunction nanoparticles(NPs)rich in oxygen vacancies embedded in mesoporous walls of nitrogen-doped hollow carbon nanoboxes coupled with nitrogen-doped carbon nanotubes(P-Co/CoOV@NHCNB@NCNT)are well designed through zeolite-imidazole framework(ZIF-67)carbonization,chemical vapor deposition,and O_(2) plasma *** a result,the threedimensional NHCNBs coupled with NCNTs and unique heterojunction with rich oxygen vacancies reduce the charge transport resistance and accelerate the catalytic reaction rate of the P-Co/CoOV@NHCNB@NCNT,and they display exceedingly good electrocatalytic performance for oxygen reduction reaction(ORR,halfwave potential[EORR,1/2=0.855 V *** hydrogen electrode])and oxygen evolution reaction(OER,overpotential(η_(OER,10)=377mV@10mA cm^(−2)),which exceeds that of the commercial Pt/C+RuO_(2) and most of the formerly reported ***,both the aqueous and flexible foldable all-solid-state rechargeable zinc-air batteries(ZABs)assembled with the P-Co/CoOV@NHCNB@NCNT catalyst reveal a large maximum power density and outstanding long-term cycling ***-principles density functional theory calculations show that the formation of heterojunctions and oxygen vacancies enhances conductivity,reduces reaction energy barriers,and accelerates reaction kinetics *** work opens up a new avenue for the facile construction of highly active,structurally stable,and cost-effective bifunctional catalysts for ZABs.

关键词： heterojunction oxygen evolution/reduction reaction oxygen vacancies rechargeable zinc–air battery three‐dimensional nitrogen‐doped hollow carbon nanoboxes

Deadline-Constrained and Cost-Effective Multi-Workflow Scheduling with Uncertainty in Cloud Control Systems

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Journal of Systems Science & Complexity 2024年第5期37卷 1861-1886页

作者： ye Lingjuan YANG Liwen XIA Yuanqing ZHAN Yufeng ZHAO Xinchao School of Science Beijing University of Posts and Telecommunications Key Laboratory of Mathematics and Information Networks Beijing University of Posts and Telecommunications Ministry of Education School of Automation Nanjing University of Information Science and Technology School of Automation Beijing Institute of Technology

In cloud control systems, generating an efficient and economical workflow scheduling strategy for deadline-constrained workflow applications, especially in uncertain multi-workflow dynamic scheduling processes, is a crucial challenge. To optimize the total cost of workflow scheduling, the authors propose a cost-driven heuristic scheduling algorithm F-MWSA which consists of two phases:Fuzzy deadline distribution and fuzzy task scheduling. In the fuzzy deadline distribution phase, a new workflow deadline distribution strategy with fuzziness is designed to obtain the sub-deadline constraint of each task. The fuzzy task scheduling phase focuses on a cost-effective strategy to assign tasks to cloud resources, reducing multi-workflow scheduling costs. Performance evaluations on five real-world workflows demonstrate that the proposed F-MWSA outperforms the baseline policy in terms of total cost, success ratio, resource utilization, and makespan.

关键词： Cloud computing cost-effective deadline constraint multi-workflow scheduling uncertainty

Influence of vibration on the lubrication effect of a splash-lubricated gearbox

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第4期25卷 324-339页

作者： Yi LIU Kailin ZHANG Shuai SHAO Hongxu XIANG Zhijian ye State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong UniversityChengdu 610031China

In this study,we investigate the effect of rail vibrations on the lubrication and efficiency of a splash-lubricated gearbox;specifically,the gearbox of a rail-transit vehicle.A high-fidelity 3D numerical model of the gearbox in a moving reference system is described,as well as computational fluid dynamics(CFD)simulations of the gearbox with different vibration *** effects of rotational speed,oil-immersion depth,and different oil-injection volume rates on lubrication and efficiency are *** propose a method of evaluating the internal lubrication condition of a splash-lubricated gearbox and quantitatively compare the effects of different operating parameters on lubrication and ***,our experiment to verify the feasibility of the simulation method is *** results show that with vibration,the churning loss and oil supply for the bearings are significantly higher than those under static *** addition,among different vibrational directions,lateral vibration has the greatest influence on the lubrication condition and efficiency of the *** the studied railway-vehicle gearbox,the best lubrication condition is achieved at a rotational speed of 1600 r/min and an oil-immersion depth of two times the tooth height(***).Rotational speed is the operating parameter that has the most significant effect on the lubrication and efficiencyofthegearbox.

关键词： Comprehensive lubrication evaluation Churning loss Moving reference system Splash lubrication Vibrational excitation Gearbox

Rapid Energy Exchange between In Situ Formed Bromine Vacancies and CO_(2)Molecules Enhances CO_(2)Photoreduction

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Research 2024年第2期2023卷 763-771页

作者： Qin Ren ye He Hong Wang Yanjuan Sun Fan Dong Research Center for Environmental and Energy Catalysis Institute of Fundamental and Frontier SciencesUniversity of Electronic Science and Technology of ChinaChengdu 611731China School of Resources and Environment University of Electronic Science and Technology of ChinaChengdu 611731China

Photocatalytic reduction of CO_(2)into fuels provides a prospective tactic for regulating the global carbon balance utilizing renewable solar ***,CO_(2)molecules are difficult to activate and reduce due to the thermodynamic stability and chemical *** this work,we develop a novel strategy to promote the adsorption and activation of CO_(2)molecules via the rapid energy exchange between the photoinduced Br vacancies and CO_(2)*** in situ continuous wave-electron paramagnetic resonance(cw-EPR)and pulsed EPR technologies,we observe that the spin-spin relaxation time(T_(2))of BiOBr is decreased by 198 ns during the CO_(2)photoreduction reaction,which is further confirmed by the broadened EPR *** result reveals that there is an energy exchange interaction between in situ formed Br vacancies and CO_(2)molecules,which promotes the formation of high-energy CO_(2)molecules to facilitate the subsequent reduction *** addition,theoretical calculations indicate that the bended CO_(2)adsorption configuration on the surface of BiOBr with Br vacancies caused the decrease of the lowest unoccupied molecular orbital of the CO_(2)molecule,which makes it easier for CO_(2)molecules to acquire electrons and get *** situ diffuse reflectance infrared Fourier transform spectroscopy further shows that the activated CO_(2)molecules are favorably converted to key intermediates of COOH*,resulting in a CO generation rate of 9.1μmol g^(-1)h^(-1)and a selectivity of 100%.This study elucidates the underlying mechanism of CO_(2)activation at active sites and deepens the understanding of CO_(2)photoreduction reaction.

关键词： reaction. adsorption activation

Estimation of the anisotropy of hydraulic conductivity through 3D fracture networks using the directional geological entropy

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International Journal of Mining Science and Technology 2024年第2期34卷 137-148页

作者： Chuangbing Zhou Zuyang ye Chi Yao Xincheng Fan Feng Xiong School of Infrastructure Engineering Nanchang UniversityNanchang 330031China b School of Resource and Environmental Engineering Wuhan University of Science and TechnologyWuhan 430081China School of Engineering China University of GeosciencesWuhan 430074China

With an extension of the geological entropy concept in porous media,the approach called directional entrogram is applied to link hydraulic behavior to the anisotropy of the 3D fracture networks.A metric called directional entropic scale is used to measure the anisotropy of spatial order in different *** with the traditional connectivity indexes based on the statistics of fracture geometry,the directional entropic scale is capable to quantify the anisotropy of connectivity and hydraulic conductivity in heterogeneous 3D fracture *** to the numerical analysis of directional entrogram and fluid flow in a number of the 3D fracture networks,the hydraulic conductivities and entropic scales in different directions both increase with spatial order(i.e.,trace length decreasing and spacing increasing)and are independent of the dip *** a result,the nonlinear correlation between the hydraulic conductivities and entropic scales from different directions can be unified as quadratic polynomial function,which can shed light on the anisotropic effect of spatial order and global entropy on the heterogeneous hydraulic behaviors.

关键词： 3D fracture network Geological entropy Directional entropic scale Anisotropy Hydraulic conductivity

Clifford Deformations of Koszul Frobenius Algebras and Noncommutative Quadrics

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Algebra Colloquium 2024年第1期31卷 63-82页

作者： Jiwei He Yu ye Department of Mathematics Hangzhou Normal UniversityHangzhou 311121China School of Mathematical Sciences University of Science and Technology of China Hefei 230026China

A Clifford deformation of a Koszul Frobenius algebra E is a finite dimensional Z_(2)-graded algebra E(θ),which corresponds to a noncommutative quadric hypersurface E^(!)/(z)for some central regular element z∈E_(2)^(!).It turns out that the bounded derived category D^(b)(gr_(Z_(2))E(θ))is equivalent to the stable category of the maximal Cohen-Macaulay modules over E^(!)/(z)provided that E!is *** a consequence,E^(!)/(z)is a noncommutative isolated singularity if and only if the corresponding Clifford deformation E(θ)is a semisimple Z_(2)-graded *** preceding equivalence of triangulated categories also indicates that Clifford deformations of trivial extensions of a Koszul Frobenius algebra are related to Knörrer's periodicity theorem for quadric *** an application,we recover Knörrer's periodicity theorem without using matrix factorizations.

关键词： Koszul Frobenius algebra Clifford deformation noncommutative quadric hypersurface maximal Cohen-Macaulay module