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Review and comparison of methods and benchmarks for automatic modal identification based on stabilization diagram

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第2期11卷 209-224页

作者： Min he Peng liang Jiuxian Liu Zhiqiang liang School of Architecture and Civil Engineering Xi'an University of Science and TechnologyXi'an 710064China School of Highway Chang'an UniversityXi'an 710064China

Automatic modal identification via automatically interpreting the stabilization diagram provides key technique in bridge structural health monitoring.This paper reviews the progress in the area of automatic modal identification based on interpreting the stabilization diagram.The whole identification process is divided into four steps from establishing the stabilization diagram to removing the outliers in the identification results.The criteria and algorithms used in each step in the existing studies are carefully summarized and classified.Comparisons between typical methods in cleaning and interpreting the stabilization diagram are also conducted.Real structure benchmarks used in the existing studies to validate the proposed automatic modal identification methods are also summarized.Based on the review and comparison,the specific ratio method for cleaning the stabilization diagram,the hierarchical clustering method for interpreting the stabilization diagram and the adjusted boxplot for removing the outliers in the identification results are the most suitable methods for each step.The key point of automatic modal identification based on interpreting the stabilization diagram has also discussed,and it is recommended to pay more attention to cleaning the stabilization diagram.Future study about automatic modal identification under situation with very few sensors deployed should be more concerned.This review aims to help researchers and practitioners in implementing existing automatic modal identification algorithms effectively and developing more suitable and practical methods for civil engineering structures in the future.

关键词： Bridge structural health monitoring Automatic modal identification Stabilization diagram Eriteria and methods Real structure benchmarks

High-Order Two-Scale Asymptotic Paradigm for the Elastodynamic Homogenization of Periodic Composites

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Acta Mechanica Solida Sinica 2024年第1期37卷 124-138页

作者： Wei-Zhi Luo Mu he liang Xia Qi-Chang he State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China Laboratoire Modélisation et Simulation Multi-Echelle MSME UMR 8208 CNRSUniversite Gustave Eiffel77454 Marne-la-ValléeFrance

The classical two-scale asymptotic paradigm provides macroscopic and microscopic analyses for the elastodynamic homogenization of periodic composites based on the spatial or/and temporal variable,which offers an approximate framework for the asymptotic homogenization analysis of the motion equation.However,in this framework,the growing complexity of the homogenization formulation gradually becomes an obstacle as the asymptotic order increases.In such a context,a compact,fast,and accurate asymptotic paradigm is developed.This work reviews the high-order spatial two-scale asymptotic paradigm with the effective displacement field representation and optimizes the implementation by symmetrizing the tensor to be determined.Remarkably,the modified implementation gets rid of the excessive memory consumption required for computing the high-order tensor,which is demonstrated by representative one-and two-dimensional cases.The numerical results show that(1)the contrast of the material parameters between media in composites directly affects the convergence rate of the asymptotic results for the homogenization of periodic composites,(2)the convergence error of the asymptotic results mainly comes from the truncation error of the modified asymptotic homogenized motion equation,and(3)the excessive norm of the normalized wavenumber vector in the two-dimensional inclusion case may lead to a non-convergence of the asymptotic results.

关键词： Composites Homogenization Asymptotic analysis Dynamics Dispersion

Gelatin-Based Metamaterial Hydrogel Films with High Conformality for Ultra-Soft Tissue Monitoring

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Nano-Micro Letters 2024年第2期16卷 347-364页

作者： Yuewei Chen Yanyan Zhou Zihe Hu Weiying Lu Zhuang Li Ning Gao nian Liu Yuanrong Li Jing he Qing Gao Zhijian Xie Jiachun Li Yong he State Key Laboratory of Fluid Power and Mechatronic Systems School of Mechanical EngineeringZhejiang UniversityHangzhou 310027People’s Republic of China School of Mechanical Engineering Guizhou UniversityGuiyang 550025People’s Republic of China Stomatology Hospital School of StomatologyZhejiang University School of MedicineClinical Research Center for Oral Diseases of Zhejiang ProvinceKey Laboratory of Oral Biomedical Research of Zhejiang ProvinceCancer Center of Zhejiang UniversityHangzhou 310006People’s Republic of China

Implantable hydrogel-based bioelectronics(IHB)can precisely monitor human health and diagnose diseases.However,achieving biodegradability,biocompatibility,and high conformality with soft tissues poses significant challenges for IHB.Gelatin is the most suitable candidate for IHB since it is a collagen hydrolysate and a substantial part of the extracellular matrix found naturally in most tissues.This study used 3D printing ultrafine fiber networks with metamaterial design to embed into ultra-low elastic modulus hydrogel to create a novel gelatin-based conductive film(GCF)with mechanical programmability.The regulation of GCF nearly covers soft tissue mechanics,an elastic modulus from 20 to 420 kPa,and a Poisson’s ratio from-0.25 to 0.52.The negative Poisson’s ratio promotes conformality with soft tissues to improve the efficiency of biological interfaces.The GCF can monitor heartbeat signals and respiratory rate by determining cardiac deformation due to its high conformability.Notably,the gelatin characteristics of the biodegradable GCF enable the sensor to monitor and support tissue restoration.The GCF metamaterial design offers a unique idea for bioelectronics to develop implantable sensors that integrate monitoring and tissue repair and a customized method for endowing implanted sensors to be highly conformal with soft tissues.

关键词： Implantable hydrogel-based bioelectronics Conformality 3D printing Metamaterial design

Optimal Model Average Prediction in Orthogonal Kriging Models

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Journal of Systems Science & Complexity 2024年第3期37卷 1080-1099页

作者： WANG Jun he Jiabei liang Hua LI Xinmin School of Mathematics and Statistics Qingdao UniversityQingdao 266071China Department of Statistics George Washington UniversityWashington DC 20052USA

The main objective of this paper is to consider model averaging methods for kriging models.This paper proposes a Mallows model averaging procedure for the orthogonal kriging model and demonstrate the asymptotic optimality of the model averaging estimators in terms of mean square error.Simulation studies are conducted to evaluate the performance of the proposed method and compare it with the competitors to demonstrate its superiority.The authors also analyse a real dataset for an illustration.

关键词： Asymptotic optimality Mallows criterion optimal model averaging orthogonal kriging model

Research on Credit Default Swaps Pricing Considering Moral Hazard Incentive under Reduce-Form Model

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Journal of Systems Science and Systems Engineering 2024年第3期33卷 311-329页

作者： liang Wu Kangjie he Zhe Guo School of Mathematical Science Henan Institute of Science and TechnologyXinxiang453003China Public Front Office Department Industrial and Commercial Bank of ChinaZhengzhou450000China

Equilibrium pricing of credit default swaps(CDS)promotes efficient identification of credit risk in the market,which in turn leads to efficient allocation of resources.However,even when CDS have been priced in equilibrium,i.e.,when premiums are equal to anticipated payments,the moral hazard incentives of CDS buyers increase with CDS transactions.Consequentially,it becomes an interesting research direction to study the impact of moral hazard incentives on the trading mechanism or pricing of derivatives(CDS).Most of the existing literature on the impact of moral hazard incentives in CDS pricing on derivatives trading mechanisms takes a macro perspective and focuses on the agreement risk effect.The literature exploring the analysis of the impact of moral hazard on the probability of agreement default from a micro perspective is not yet available.With this in mind,this paper focuses on the mechanisms by which“fraud”,an extreme manifestation of micro-moral hazard incentives,affects the probability of default.This paper introduces for the first time the concept of“claiming fraud”by credit protection buyers,which is different from the macro perspective of moral hazard incentives,and thus defines a specific extreme form of moral hazard incentives.Meanwhile,to address the intrinsic feature of the lack of economic explanatory power of the reduce-form model,this paper introduces a moral hazard incentive factor into the reduce-form model,and proposes a moral hazard state variable as a function of the asset value of the reference entity,which gives the reduce-form model strong economic explanatory power,and the default predictability is reduced by the description of the reduce-form model.In terms of the object of study,this paper considers the issue of moral hazard incentives in the presence of claiming fraud in two reference entities to further explore the impact of moral hazard incentives on default protection at the micro level in terms of cyclic default.Finally,based on the analysis of the results of the numerical simulat

关键词： Financial engineering moral hazard incentive claiming fraud reduce-form model probability of default calculation CDS pricing

Autoimmune hepatitis-primary biliary cholangitis overlap syndrome complicated by various autoimmune diseases:A case report

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World Journal of Clinical Cases 2024年第6期12卷 1174-1181页

作者： Yu-Jie Qin Ting Gao Xing-nian Zhou Ming-liang Cheng Hong Li Clinical Medicine School of Guizhou Medical University Guiyang 550025Guizhou ProvinceChina Department of Pathology The Affiliated Hospital of Guizhou Medical UniversityGuiyang 550025Guizhou ProvinceChina Department of Infectious Diseases Guizhou Medical UniversityGuiyang 550025Guizhou ProvinceChina Department of Infectious Diseases Guizhou Provincial People's HospitalGuiyang 550025Guizhou ProvinceChina

BACKGROUND Autoimmune hepatitis(AIH)and primary biliary cholangitis(PBC)are two common clinical autoimmune liver diseases,and some patients have both diseases;this feature is called AIH-PBC overlap syndrome.Autoimmune thyroid disease(AITD)is the most frequently overlapping extrahepatic autoimmune disease.Immunoglobulin(IgG)4-related disease is an autoimmune disease recognized in recent years,characterized by elevated serum IgG4 levels and infiltration of IgG4-positive plasma cells in tissues.CASE SUMMARY A 68-year-old female patient was admitted with a history of right upper quadrant pain,anorexia,and jaundice on physical examination.Laboratory examination revealed elevated liver enzymes,multiple positive autoantibodies associated with liver and thyroid disease,and imaging and biopsy suggestive of pancreatitis,hepatitis,and PBC.A diagnosis was made of a rare and complex overlap syndrome of AIH,PBC,AITD,and IgG4-related disease.Laboratory features improved on treatment with ursodeoxycholic acid,methylprednisolone,and azathioprine.CONCLUSION This case highlights the importance of screening patients with autoimmune diseases for related conditions.

关键词： Overlap syndrome Autoimmune hepatitis Primary biliary cholangitis Primary sclerosing cholangitis Autoimmune thyroid disease Case report

Nontraditional energy-assisted mechanical machining of difficult-to-cut materials and components in aerospace community:a comparative analysis

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International Journal of Extreme Manufacturing 2024年第2期6卷 190-271页

作者： Guolong Zhao Biao Zhao Wenfeng Ding Lianjia Xin Zhiwen nian Jianhao Peng Ning he Jiuhua Xu College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016People’s Republic of China

The aerospace community widely uses difficult-to-cut materials,such as titanium alloys,high-temperature alloys,metal/ceramic/polymer matrix composites,hard and brittle materials,and geometrically complex components,such as thin-walled structures,microchannels,and complex surfaces.Mechanical machining is the main material removal process for the vast majority of aerospace components.However,many problems exist,including severe and rapid tool wear,low machining efficiency,and poor surface integrity.Nontraditional energy-assisted mechanical machining is a hybrid process that uses nontraditional energies(vibration,laser,electricity,etc)to improve the machinability of local materials and decrease the burden of mechanical machining.This provides a feasible and promising method to improve the material removal rate and surface quality,reduce process forces,and prolong tool life.However,systematic reviews of this technology are lacking with respect to the current research status and development direction.This paper reviews the recent progress in the nontraditional energy-assisted mechanical machining of difficult-to-cut materials and components in the aerospace community.In addition,this paper focuses on the processing principles,material responses under nontraditional energy,resultant forces and temperatures,material removal mechanisms,and applications of these processes,including vibration-,laser-,electric-,magnetic-,chemical-,advanced coolant-,and hybrid nontraditional energy-assisted mechanical machining.Finally,a comprehensive summary of the principles,advantages,and limitations of each hybrid process is provided,and future perspectives on forward design,device development,and sustainability of nontraditional energy-assisted mechanical machining processes are discussed.

关键词： difficult-to-cut materials geometrically complex components nontraditional energy mechanical machining aerospace community

CO_(2) capture and utilization with solid waste

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Green Chemical Engineering 2022年第3期3卷 199-209页

作者： Wei-Hang Xie heng Li Meng Yang liang-nian he Hong-Ru Li State Key Laboratory and Institute of Elemento-Organic Chemistry College of ChemistryNankai UniversityTianjin300071China College of Pharmacy Nankai UniversityTianjin300350China

Nowadays,the massive consumption of fossil fuels and the resulting excessive emission of carbon dioxide(CO_(2))have broken the original carbon balance of nature,resulting in global warming and the consequent detrimental environmental impacts.To address these issues,various initiatives have been proposed,among which CO_(2) cap-ture and utilization(CCU)is considered as the direct way to mitigate the accumulation of CO_(2) in the atmosphere.Although a plethora of CO_(2) capture reagents and utilization routes have been developed,the cost of CO_(2) capture reagents as well as the amount of CO_(2) utilization still encounters limitations.Recently,CCU with solid wastes have attracted sustained attention due to its ability to synchronize CO_(2) fixation with solid wastes utilization.Especially,the huge amount and low cost of the solid wastes can promote the economic fixation of CO_(2) and thus contribute significantly to the carbon sink.Given the tremendous utility of this strategy,this review article summarizes the state-of-the-art of CO_(2) capture and utilization with solid wastes such as steel slag,concrete waste,fly ash,red mud,calcium carbide residue,and biomass etc.And three parts including CO_(2) mineralization,solid waste-based catalyst promoted CO_(2) transformation,and collaborative transformation of CO_(2) and solid waste are introduced according to the roles of solid waste in CO_(2) utilization.We hope this review can arouse broad concern and spur further development in this field.

关键词： Carbon capture CO_(2)utilization Solid waste Sustainable chemistry Value-added product

Novel Method for Evaluating the Aging of Aviation Turbine Engine Oils via High-Temperature Bearing Deposit Tests

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China Petroleum Processing & Petrochemical Technology 2024年第1期26卷 67-77页

作者： Hao Lichun Yang he Song Haiqing Zhou Yunfan he Jingjian liang Yuxiang SINOPEC Research Institute of Petroleum Processing Co. Ltd.Beijing 100083

Aviation turbine engine oils require excellent thermal-oxidative stability because of their high-temperature environments.High-temperature bearing deposit testing is a mandatory method for measuring the thermal-oxidative performance of aviation lubricant oils,and the relevant apparatus was improved in the present study.Two different commercial aviation turbine engine oils were tested,one with standard performance(known as the SL oil)and the other with high thermal stability,and their thermal-oxidative stability characteristics were evaluated.After 100 h of high-temperature bearing testing,the SL oil was analyzed by using various analytical techniques to investigate its thermal-oxidative process in the bearing test,with its thermal-oxidative degradation mechanism also being discussed.The results indicate that the developed high-temperature bearing apparatus easily meets the test requirements of method 3410.1 in standard FED-STD-791D.The viscosity and total acid number(TAN)of the SL oil increased with the bearing test time,and various deposits were produced in the bearing test,with the micro-particles of the carbon deposits being sphere-like,rod-like,and sheet-like in appearance.The antioxidant additives in the oil were consumed very rapidly in the first 30 h of the bearing test,with N-phenyl-1-naphthylamine being consumed faster than dioctyldiphenylamine.Overall,the oil thermal-oxidative process involves very complex physical and chemical mechanisms.

关键词： aviation turbine engine oil high-temperature bearing deposit test thermal-oxidative degradation antioxidant additives