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Strain Gradient Finite Element Formulation of Flexoelectricity in Ferroelectric Material Based on Phase-Field Method

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ACTA MECHANICA SOLIDA SINICA 2024年第4期37卷 570-579页

作者： Wang, Shuai Su, Hengchang yi, min Shao, Li-Hua Beihang Univ Inst Solid Mech Sch Aeronaut Sci & Engn Natl Key Lab Strength & Struct Integr Beijing 100191 Peoples R China Nanjing Univ Aeronaut & Astronaut State Key Lab Mech & Control Aerosp Struct Nanjing 210016 Peoples R China Nanjing Univ Aeronaut & Astronaut Inst Frontier Sci Nanjing 210016 Peoples R China Nanjing Univ Aeronaut & Astronaut Key Lab Intelligent Nano Mat & Devices Minist Educ Nanjing 210016 Peoples R China Nanjing Univ Aeronaut & Astronaut Coll Aerosp Engn Nanjing 210016 Peoples R China

Flexoelectricity is a two-way coupling effect between the strain gradient and electric field that exists in all dielectrics, regardless of point group symmetry. However, the high-order derivatives of displacements involved in the strain gradient pose challenges in solving electromechanical coupling problems incorporating the flexoelectric effect. In this study, we formulate a phase-field model for ferroelectric materials considering the flexoelectric effect. A four-node quadrilateral element with 20 degrees of freedom is constructed without introducing high-order shape functions. The microstructure evolution of domains is described by an independent order parameter, namely the spontaneous polarization governed by the time-dependent Ginzburg-Landau theory. The model is developed based on a thermodynamic framework, in which a set of microforces is introduced to construct the constitutive relation and evolution equation. For the flexoelectric part of electric enthalpy, the strain gradient is determined by interpolating the mechanical strain at the node via the values of Gaussian integration points in the isoparametric space. The model is shown to be capable of reproducing the classic analytical solution of dielectric materials incorporating the flexoelectric contribution. The model is verified by duplicating some typical phenomena in flexoelectricity in cylindrical tubes and truncated pyramids. A comparison is made between the polarization distribution in dielectrics and ferroelectrics. The model can reproduce the solution to the boundary value problem of the cylindrical flexoelectric tube, and demonstrate domain twisting at domain walls in ferroelectrics considering the flexoelectric effect.

关键词： Flexoelectricity Phase-field method Ferroelectrics Domain configuration MODELS FRAMEWORK SYSTEMS STRESS

Theoretical study on magnetocaloric effect and its electric-field regulation in CrI_(3)/metal heterostructure

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Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 134-141页

作者： Weiwei He Ziming Tang Qihua Gong min yi Wanlin Guo State Key Laboratory of Mechanics and Control for Aerospace Structures Key Laboratory for Intelligent Nano Materials and Devices of Ministry of EducationInstitute for Frontier ScienceNanjing University of Aeronautics and AstronauticsNanjing 210016China MIIT Key Laboratory of Aerospace Information Materials and Physics College of PhysicsNanjing University of Aeronautics and AstronauticsNanjing 211106China

The extraordinary properties of a heterostructure by stacking atom-thick van der Waals(vdW)magnets have been extensively ***,the magnetocaloric effect(MCE)of heterostructures that are based on monolayer magnets remains to be ***,we deliberate MCE of vd W heterostructure composed of a monolayer CrI_(3)and metal atomic layers(Ag,Hf,Au,and Pb).It is revealed that heterostructure engineering by introducing metal substrate can improve MCE of CrI_(3),particularly boosting relative cooling power to 471.72μJ m^(-2)and adiabatic temperature change to 2.1 K at 5 T for CrI_(3)/*** improved MCE is ascribed to the enhancement of magnetic moment and intralayer exchange coupling in CrI_(3)due to the CrI_(3)/metal heterointerface induced charge *** field is further found to tune MCE of CrI_(3)in heterostructures and could shift the peak temperature by around 10 K in CrI_(3)/Hf,thus manipulating the working temperature window of *** theoretical results could enrich the research on low-dimensional magnetocaloric materials.

关键词： magnetocaloric effect heterostructure metal substrate

Hemoglobin loss method calculates blood loss during pancreaticoduodenectomy and predicts bleeding-related risk factors

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World Journal of Gastrointestinal Surgery 2024年第2期16卷 419-428页

作者： Chao Yu yi-min Lin Guo-Zhe Xian Department of Hepatobiliary Surgery Shandong Provincial Hospital Affiliated to Shandong First Medical UniversityJinan 250021Shandong ProvinceChina

BACKGROUND The common clinical method to evaluate blood loss during pancreaticoduoden-ectomy(PD)is visual inspection,but most scholars believe that this method is extremely subjective and ***,there is no accurate,objective me-thod to evaluate the amount of blood loss in PD *** retrospectively analyzed the clinical data of 341 patients who underwent PD in Shandong Provincial Hospital from March 2017 to February *** to different surgical methods,they were divided into an open PD(OPD)group and a laparoscopic PD(LPD)*** differences and correlations between the in-traoperative estimation of blood loss(IEBL)obtained by visual inspection and the intraoperative calculation of blood loss(ICBL)obtained using the Hb loss method were ***,IEBL and perioperative calculation of blood loss(PCBL)were compared between the two groups,and single-factor regression analysis was *** There was no statistically significant difference in the preoperative general patient information between the two groups(P>0.05).PD had an ICBL of 743.2(393.0,1173.1)mL and an IEBL of 100.0(50.0,300.0)mL(P200μmol/L(95%CI:7.09-644.26;P=0.045)were independent risk factors for *** ICBLs of the LPD group and OPD group were 767.7(435.4,1249.0)mL and 663.8(347.7,1138.2)mL,respectively(P>0.05).The IEBL of the LPD group 200.0(50.0,200.0)mL was slightly greater than that of the OPD group 100.0(50.0,300.0)mL(P>0.05).PCBL was greater in the LPD group than the OPD group[1061.6(612.3,1632.3)mL vs 806.1(375.9,1347.6)mL](P<0.05).CONCLUSION The ICBL in patients who underwent PD was greater than

关键词： Pancreaticoduodenectomy Hemoglobin loss Calculated blood loss Estimated blood loss

Publication trends of Leber congenital amaurosis researches:a bibliometric study during 2002-2022

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International Journal of Ophthalmology(English edition) 2024年第8期17卷 1501-1509页

作者： Xiao-Xu Huang yi-min Wang min-Yue Xie yi-Qing Sun Xiao-Huan Zhao Yu-Hong Chen Jie-Qiong Chen Si-Yang Han min-Wen Zhou Xiao-Dong Sun Department of Ophthalmology Shanghai General HospitalShanghai Jiao Tong University School of MedicineShanghai 200080China National Clinical Research Center for Eye Disease Shanghai 200080China Shanghai Key Laboratory of Ocular Fundus Diseases Shanghai 200080China Shanghai Engineering Center for Visual Science and Photomedicine Shanghai 200080China Department of Ophthalmology Zhongshan HospitalFudan UniversityShanghai 200030China Beijing Tongren Hospital Capital Medical UniversityBeijing 100054China Eberly College of Science Penn State UniversityUniversity Park 16802-1503United States

AIM:To analyze the changes in scientific output relating to Leber congenital amaurosis(LCA)and forecast the study trends in this ***:All of the publications in the field of LCA from 2002 to 2022 were collected from Web of Science(WOS)*** analyzed the quantity(number of publications),quality(citation and H-index)and development trends(relative research interest,RRI)of published LCA research over the last two ***,VOSviewer software was applied to define the co-occurrence network of keywords in this ***:A total of 2158 publications were ultimately *** found that the focus on LCA kept rising and peaked in 2015 and 2018,which is consistent with the development trend of gene *** USA has contributed most to this field with 1162 publications,56674 citations and the highest H-index value(116).The keywords analysis was divided into five clusters to show the hotspots in the field of LCA,namely mechanism-related,genotype-related,local phenotype-related,system phenotype-related,and *** also identified gene therapy and antiretinal degeneration therapy as a major focus in recent ***:Our study illustrates historical research process and future development trends in LCA *** may help to guide the orientation for further clinical diagnosis,treatment and scientific research.

关键词： VOSviewer bibliometrics Leber congenital amaurosis gene therapy hotpots

Machine learning for predicting fatigue properties of additively manufactured materials

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Chinese Journal of Aeronautics 2024年第4期37卷 1-22页

作者： min yi ming XUE Peihong CONG Yang SONG Haiyang ZHANG Lingfeng WANG Liucheng ZHOU yinghong LI Wanlin GUO State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China Institute for Frontier Science Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Shenyang Engine Research Institute Shenyang 110015China Liaoning Key Laboratory of Impact Dynamics on Aero Engine Shenyang 110015China Science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi’an 710038China

Fatigue properties of materials by Additive Manufacturing(AM) depend on many factors such as AM processing parameter, microstructure, residual stress, surface roughness, porosities, post-treatments, etc. Their evaluation inevitably requires these factors combined as many as possible, thus resulting in low efficiency and high cost. In recent years, their assessment by leveraging the power of Machine Learning(ML) has gained increasing attentions. A comprehensive overview on the state-of-the-art progress of applying ML strategies to predict fatigue properties of AM materials, as well as their dependence on AM processing and post-processing parameters such as laser power, scanning speed, layer height, hatch distance, built direction, post-heat temperature,etc., were presented. A few attempts in employing Feedforward Neural Network(FNN), Convolutional Neural Network(CNN), Adaptive Network-Based Fuzzy Inference System(ANFIS), Support Vector Machine(SVM) and Random Forest(RF) to predict fatigue life and RF to predict fatigue crack growth rate are summarized. The ML models for predicting AM materials' fatigue properties are found intrinsically similar to the commonly used ones, but are modified to involve AM features. Finally, an outlook for challenges(i.e., small dataset, multifarious features,overfitting, low interpretability, and unable extension from AM material data to structure life) and potential solutions for the ML prediction of AM materials' fatigue properties is provided.

关键词： Additive manufacturing Machine learning Fatigue life Fatigue crack growth rate Prediction

Flexible and multifunctional triboelectric nanogenerator based on liquid metal/polyvinyl alcohol hydrogel for energy harvesting and self-powered wearable human-machine interaction

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Rare Metals 2024年第3期43卷 1186-1196页

作者： Hou-Wang Zhou Cong Zhao Ze-Yu Zhao Jun-Chen Jiang Hui-Le Jin Shun Wang Shuang Pan min-yi Xu yi-Huang Chen Hai-ming Jin Department of Orthopaedics The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical UniversityWenzhou325027China College of Chemistry and Materials Engineering Wenzhou UniversityWenzhou325035China Dalian Key Laboratory of Marine Micro/Nano Energy and Self-Powered Systems Marine Engineering CollegeDalian Maritime UniversityDalian116026China

Hydrogel-based triboelectric nanoge nerator(TENG)has a promising applied prospect in wearable electronic ***,its low performance,poor stability,insufficient recyclability and inferior self-healing seriously hinder its ***,we report a robust route to a liquid metal(LM)/polyvinyl alcohol(PVA)hydrogel-based TENG(LP-TENG).Owing to the intrinsically liquid feature of conductive LM within the flexible PVA hydrogel,the as-prepared LP-TENG exhibited comprehensiye advantages of adaptability,biocompatibility,outstanding electrical performance,superior stability,recyclability and diverse applications,which were unattainable by traditional ***,the LP-TENG delivered appealing open circuit voltage of 250 V,short circuit current of 4μA and transferred charge of 120 nC with high stability,outperforming most advanced TENG *** LP-TENG was successfully employed for versatile applications with multifunctionality,including human motion detection,handwriting recognition,energy collection,message transmission and human-machine *** work presents significant prospects for crafting advanced materials and devices in the fields of wearable electronics,flexible skin and smart robots.

关键词： Liquid metal Hydrogel Wearable TENG Multifunctionality Human-machine interaction

Association between luteinizing hormone level decrease on the triggering day and pregnancy outcome for in vitro fertilization/intracytoplasmic sperm injection patients following gonadotropin-releasing hormone antagonist protocol: a retrospective cohor

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生殖与发育医学(英文) 2024年第1期08卷 8-17页

作者： Li Qing-Fang Tang min-Yue Wang Gui-Quan Chen Xi-Jing Feng Guo-Fang Zhu yi-min Women’s Hospital School of Medicine 3. Zhejiang University 4. 1 Xueshi Road 5. Hangzhou 310006 6. China

Objective: Optimal luteinizing hormone (LH) levels forin vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) patients following the gonadotropin-releasing hormone (GnRH) antagonist protocol remain controversial. This study aimed to estimate the association between serum LH levels on the triggering day (LHLOT) and clinical pregnancy outcomes in IVF/ICSI patients following the GnRH antagonist ***: We enrolled 4743 IVF/ICSI cycles using flexible or fixed GnRH antagonist protocols between January 2017 and June 2021. The patients were stratified into four groups according to the LHLOT quartiles (Q1–Q4). Each group was further divided into two subgroups according to the median basal LH/LHLOT. The main outcomes were clinical pregnancy, birth, and miscarriage rates. Secondary outcomes were oocyte yield, number of MII, fertilized oocytes (2PN), and high-quality ***: Serum LHLOT levels were negatively correlated with oocyte yield and the numbers of MII, 2PN, and high-quality embryos. Reproductive outcomes were compared among the different quartiles and subgroups. The absolute difference in the clinical pregnancy rates between the Q4 and Q1 groups was 6.4% (47.2%vs. 40.8%,P 3.04 and ≤3.04 were 32.7% and 48.6% (P 2.14 and ≤2.14 were 50.2% and 41.9%, respectively (P <0.05). The greater the decrease in LH levels, the lower the oocyte maturation rate across all ***: According to the LHLOT quartiles, the Q1 of serum LHLOT <1.43 IU/L may result in a higher number of oocytes but reduced oocyte maturation and lower clinical pregnancy rates. A decrease in LH levels by approximately 2.14 to 3.04 times compared to basal LH levels may lead to higher clinical pregnancy rates in IVF/ICSI patients following the GnRH antagonist protocol.

关键词： GnRH antagonist IVF/ICSI Luteinizing hormone Ovarian stimulation Reproductive outcomes

How Sense of Ritual in Tourism Impacts Tourists’Co-Creation of Tourism Experience Values:A Study Based on the Theory of Value Co-Creation

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Contemporary Social Sciences 2024年第2期9卷 67-84页

作者： yi min Zhang Guangyu Sun Genjin Southwest minzu University ChengduSichuan610041China Sichuan Agricultural University

Establishing a sense of ritual within tourism consumption scenarios offers tourists the opportunity for interactive *** upon the value co-creation theory,this study constructed an influence mechanism model to examine tourists'active engagement in the process of co-creating tourism experience *** employed Partial Least Squares Structural Equation Modeling(PLS-SEM)to empirically test the proposed *** findings demonstrate that the model constructed in the present study exhibits robust reliability,validity,and explanatory *** perception of the sense of ritual in tourism exerts a significant positive influence on tourists’co-creation of tourism experience values,thereby significantly enhancing both the communitas and flow experienced by tourists during their ***,such communitas and flow can mediate the influence of the sense of ritual in tourism on tourists’co-creation of tourism experience *** study contributes to advancing the current research on tourists’co-creation of tourism experience values and the sense of ritual in tourism,thereby providing theoretical foundations for cultivating a sense of ritual within tourism consumption scenarios.

关键词： sense of ritual in tourism tourists’co-creation of tourism experience values theory of value co-creation theory of Interaction Ritual Chains

SHA: QoS-Aware Software and Hardware Auto-Tuning for Database Systems

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Journal of Computer Science & Technology 2024年第2期39卷 369-383页

作者：李进陈全唐晓新过敏意 Department of Computer Science Shanghai Jiao Tong UniversityShanghai 200240China Department of Computer Science and Technology Shanghai University of Finance and EconomicsShanghai 200433China

While databases are widely-used in commercial user-facing services that have stringent quality-of-service(QoS)requirement,it is crucial to ensure their good performance and minimize the hardware usage at the same *** investigation shows that the optimal DBMS(database management system)software configuration varies for different user request patterns(i.e.,workloads)and hardware *** is challenging to identify the optimal software and hardware configurations for a database workload,because DBMSs have hundreds of tunable knobs,the effect of tuning a knob depends on other knobs,and the dependency relationship changes under different hardware *** this paper,we propose SHA,a software and hardware auto-tuning system for *** is comprised of a scaling-based performance predictor,a reinforcement learning(RL)based software tuner,and a QoS-aware resource *** performance predictor predicts its optimal performance with different hardware configurations and identifies the minimum amount of resources for satisfying its performance *** software tuner fine-tunes the DBMS software knobs to optimize the performance of the *** resource reallocator assigns the saved resources to other applications to improve resource utilization without incurring QoS violation of the database *** results show that SHA improves the performance of database workloads by 9.9%on average compared with a state-of-the-art solution when the hardware configuration is fixed,and improves 43.2%of resource utilization while ensuring the QoS.

关键词： auto-tuning database configuration joint tuning utilization quality-of-service(QoS)