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Modeling ocean wave propagation under sea ice covers

Acta Mechanica Sinica 2015年第1期31卷 1-15页

作者： Xin zhao hayley h. Shen Sukun Cheng department of Civil and Environmental Engineering Clarkson University

Operational ocean wave models need to work globally, yet current ocean wave models can only treat ice covered regions crudely. The purpose of this paper is to provide a brief overview of ice effects on wave propagation and different research methodology used in studying these effects. Based on its proximity to land or sea, sea ice can be classified as： landfast ice zone, shear zone, and the marginal ice zone. All ice covers attenuate wave energy. Only long swells can penetrate deep into an ice cover. Being closest to open water, wave propagation in the marginal ice zone is the most complex to model. The physical appearance of sea ice in the marginal ice zone varies. Grease ice, pancake ice, brash ice, floe aggregates, and continuous ice sheet may be found in this zone at different times and locations. These types of ice are formed under different thermalmechanical forcing. There are three classic models that describe wave propagation through an idealized ice cover： mass loading, thin elastic plate, and viscous layer models. From physi cal arguments we may conjecture that mass loading model is suitable for disjoint aggregates of ice floes much smaller than the wavelength, thin elastic plate model is suitable for a con tinuous ice sheet, and the viscous layer model is suitable for grease ice. For different sea ice types we may need different wave ice interaction models. A recently proposed viscoelas tic model is able to synthesize all three classic models into one. Under suitable limiting conditions it converges to the three previous models. The complete theoretical framework for evaluating wave propagation through various ice covers need to be implemented in the operational ocean wave models. In this review, we introduce the sea ice types, previous wave ice interaction models, wave attenuation mechanisms,the methods to calculate wave reflection and transmission between different ice covers, and the effect of ice floe breaking on shaping the sea ice morphology. Labora

关键词： Ocean waves Sea ice Cryospheric change

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Roles of Financial Innovation and Information Technology:Lessons from US Sub-prime Mortgage Crisis and Its Implications for China

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Chinese Geographical Science 2012年第3期22卷 343-355页

作者： James h LENZER JR Simon Xiaobin zhao International Center for China development Studies & department of Geography Faculty of Social Sciencesthe University of Hong KongHong KongChina

The mortgage loan has evolved from a local lending instrument into a major global security and its role is unparallel to other financial instruments in the process of financial globalization. This paper explains how technology and financial innovation transformed the mortgage loan from a local security into a premier global security traded worldwide. It examines the fundamental flaws of this process and why it does not work in regards to mortgage lending and the re-securitization products that were created through financial innovation. The findings show that regulation was unable to keep pace with financial innovation, which created an environment where actors in the financial service sector were able to behave geographically irresponsibly by using information asymmetries to their advantage by par- ticipating in moral hazard activities and engaging in other immoral and unethical business practices that were centered around localized geography, which ultimately contributed to the global financial crisis. It also examines the roll of financial innovation in regard to the Lehman Brothers Mini-Bond in hung and its role as a driving force behind China＇s newly emerging shadow banking sector. It concludes with a policy recommendation and its implication for China＇s continued economic development.

关键词： shadow banking US sub-prime mortgage crisis financial tsunami global financial crisis wealth man- agement vehicle China asset bubble

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Characteristic analysis of CO_2 switching arcs under a dC current

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Plasma Science and Technology 2018年第8期20卷 42-49页

作者： Xiaoling zhao J d YAN dengming XIAO department of Electrical Engineering Shanghai Jiao Tong UniversityShanghai 200030People＇s Republic of China department of Electrical Engineering and Electronics University of LiverpoolBrownlow HillLiverpool L69 3GJUnited Kingdom

The current interruption capability of a gas, when used in high voltage gas-blast circuit breakers,depends not only on its material properties but also the flow field since turbulence plays a dominant role in arc cooling during the interruption process. Based on available experimental results, a study of CO2 switching arcs under a dC（direct current） current in the model circuit breaker has been conducted to calibrate CO2 arc model and to analyse its electric and thermal property. Through detailed analysis of the results mechanisms responsible for the temperature distribution are identified and the domain energy transportation process of different region discussed. The present work provides significant coefficients for CO2 switching arc simulation and gives a better understanding of CO2 arc burning mechanisms.

关键词： energy transportation thermal and electric property CO2 switching arc

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Refining constitutive relation by integration of finite element simulations and Gleeble experiments

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Journal of Materials Science & Technology 2019年第6期35卷 1039-1043页

作者： d.J. Yu d.S. Xu h. W ang Z.B. zhao G.Z. Wei R. Yang College of Sciences Northeastern University Shenyang 110004 China Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Thermo-mechanical coupled finite element calculations were carried out to simulate the Gleeble compression of the samples of a titanium alloy(Ti60), and the results are analyzed and compared with the actual compression tests conducted on a Gleeble 3800 thermo-mechanical simulator. The changes in temperature, stress and strain distribution in the samples and the source of error on the constitutive relations from Gleeble hot compression test were analyzed in detail. Both simulations and experiments showed that the temperature distribution in the specimen is not uniform during hot compression, resulting in significant deformation inhomogeneity and non-ignorable error in the flow stress strain relation,invalidating the uniform strain assumption commonly assumed when extracting the constitutive relation from Gleeble tests. Based on the finite element simulations with iterative corrections, we propose a scheme to refine the constitutive relations from Gleeble tests.

关键词： Titanium alloy Constitutive relation Finite element Compression Temperature distribution

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有限性与延展性:新中国国家安全思想的演进

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国际安全研究 2025年第1期43卷 73-95,157页

作者：祁昊天赵书韫北京大学国际关系学院国家安全学系北京100871

文章从国家安全本体论、安全体系认识论与安全实践方法论三个维度考察新中国的国家安全思想,以社会主义革命和建设时期、改革开放和社会主义现代化建设新时期以及中国特色社会主义新时代进行时间分段,讨论新中国国家安全思想的演进。有... 详细信息

文章从国家安全本体论、安全体系认识论与安全实践方法论三个维度考察新中国的国家安全思想,以社会主义革命和建设时期、改革开放和社会主义现代化建设新时期以及中国特色社会主义新时代进行时间分段,讨论新中国国家安全思想的演进。有限性与延展性是这一演进过程中安全思想的连贯体现,分别涵盖了安全目标、认知与方法在各阶段静态与动态、横向与纵向的特征。虽然新中国在不同时期面临不同的安全环境和安全需求,安全形势愈加复杂,但是安全思想和实践总体符合安全有限、延展演进的特征。安全具有弹性但不可过载,不存在绝对安全的空间,而狭义的、单一领域或维度的安全亦无法有效支撑对国家安全的维护,特别是在愈加复杂和不确定的国家安全环境中更是如此。新中国国家安全思想“有限—延展”的演进特征反映了安全环境的客观变化与领导人主观能动的决策部署。

关键词：国家安全思想演进有限性延展性

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Taxonomy and phylogeny of operculate discomycetes: Pezizomycetes

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Fungal diversity 2018年第3期90卷 161-243页

作者： Anusha h.Ekanayaka Kevin d.hyde E.B.Gareth Jones Qi zhao Key Laboratory for Plant diversity and Biogeography of East Asia Kunming Institute of BotanyChinese Academy of SciencesKunming 650201YunnanChina Center of Excellence in Fungal Research Mae Fah Luang UniversityChiang Rai 57100Thailand department of Entomology and Plant Pathology Faculty of AgricultureChiang Mai UniversityChiang Mai 50200Thailand

The class Pezizomycetes is monophyletic within the subdivision Pezizomycotina. The main distinguishing character of thisclass is operculate asci, although in some taxa this character has been lost. The circumscription of the families and genericlevel delimitation in Pezizomycetes is still controversial, although several molecular phylogenetic studies have beenpublished on this group. This paper reviews 21 families of Pezizomycetes including five new families, which are introduced here, viz. Kallistoskyphaceae, Pseudombrophilaceae, Pulvinulaceae, Strobiloscyphaceae and Tarzettaceae. Moreover, this study provides a modified backbone tree based on phylogenetic analysis of five combined loci. descriptions andillustrations of representative taxa for the families are provided from collections made in China, Thailand and the UK,herbarium material from international herbaria (Fh, FLAS, h, hKAS and MA) and the literature. Pezizales separates intosix major clades. Clade 1 of Pezizales includes the families Ascobolaceae and Pezizaceae. Clade 2 is the new familyKallistoskyphaceae. Clade 3 comprises the families Caloscyphaceae, Karstenellaceae and Rhizinaceae. Clade 4 representsthe families discinaceae, helvellaceae, Morchellaceae, Tuberaceae and Underwoodia columnaris lineage. Clade 5includes Chorioactidaceae, Sarcoscyphaceae and Sarcosomataceae and Clade 6 comprises Ascodesmidaceae, Glaziellaceae, Otideaceae, Pseudombrophilaceae, Pulvinulaceae, Pyronemataceae, Strobiloscyphaceae and Tarzettaceae. Newsequence data belonging to ITS, LSU, SSU, TEF, RPB2 gene regions from 40 pezizalian species are provided here. Thepaper provides a working document for apothecial Pezizomycetes which can be modified as new data comes to light. It ishoped that by illustrating taxa we provide stimulation and interest in the operculate discomycetes, so that further research iscarried out on this remarkable, but poorly studied group of fungi.

关键词： Apothecial ascomycetes Five new families Multi-gene analysis Systematics Tuberales

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Bone tissue engineering via nanostructured calcium phosphate biomaterials and stem cells

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Bone Research 2014年第3期2卷 139-151页

作者： Ping Wang Liang zhao Jason Liu Michael d Weir Xuedong Zhou hockin h K Xu Biomaterials & Tissue Engineering division Department of Endodontics Prosthodontics and Operative Dentistry University of Maryland Dental School Baltimore MD 21201 USA State Key Laboratory of Oral diseases West China Hospital of Stomatology Sichuan University department of Orthopaedic Surgery Nanfang Hospital Southern Medical University Mechanical Engineering department University of Maryland Baltimore County Baltimore MD 21250 USA Center for Stem Cell Biology and Regenerative Medicine University of Maryland School of Medicine Baltimore MD 21201 USA

Tissue engineering is promising to meet the increasing need for bone regeneration. Nanostructured calcium phosphate （CAP） biomaterials/scaffolds are of special interest as they share chemical/crystallographic similarities to inorganic components of bone. Three applications of nano-CaP are discussed in this review： nanostructured calcium phosphate cement （CPC）; nano-CaP composites; and nano-CaP coatings. The interactions between stem cells and nano-CaP are highlighted, including cell attachment, orientation/ morphology, differentiation and in vivo bone regeneration. Several trends can be seen：（i） nano-CaP biomaterials support stem cell attachment/proliferation and induce osteogenic differentiation, in some cases even without osteogenic supplements; （ii） the influence of nano-CaP surface patterns on cell alignment is not prominent due to non-uniform distribution of nano-crystals; （iii） nano-CaP can achieve better bone regeneration than conventional CaP biomaterials; （iv） combining stem cells with nano-CaP accelerates bone regeneration, the effect of which can be further enhanced by growth factors; and （v） cell microencapsulation in nano-CaP scaffolds is promising for bone tissue engineering. These understandings would help researchers to further uncover the underlying mechanisms and interactions in nano-CaP stem cell constructs in vitro and in vivo, tailor nano-CaP composite construct design and stem cell type selection to enhance cell function and bone regeneration, and translate laboratory findings to clinical treatments.

关键词： CPC Bone tissue engineering via nanostructured calcium phosphate biomaterials and stem cells stem

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Modeling Common-Mode Current due to Asymmetric Aging of Machine Winding Insulation

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Complex System Modeling and Simulation 2023年第2期3卷 118-128页

作者： Jin zhao Aaron d.Brovont department of Electrical and Computer Engineering The University of AlabamaTuscaloosaAL 35487USA the PC Krause and Associates West LafayetteIN 47906USA

Machine stator winding insulation degradation is one of the main results of machine *** is non-negligible once this degradation process becomes asymmetric between *** traditional way to determine the insulation state of health is a partial discharge ***,this method requires the system offline,which causes production loss and extra administrative *** paper presents an idea for better characterizing the insulation machine’s state of health using common-mode(CM)behavior in the machine-drive *** the help of circuit decomposition methods and modeling tools,the CM quantities due to asymmetric aging show a unique characteristic that distinguishes itself from other differential-mode(dM)quantities in the equivalent *** is shown effective to represent the asymmetric aging effect from the detection of system leakage *** paper provides an analytical method to quantify this characteristic from mathematical approaches,and a proper approximation has been made on the CM equivalent model(CEM)such that the CM behavior is accurately *** proposed method will serve the purpose of predicting machine abnormal behavior using the simple RLC *** can adapt this method to quantify and characterize the machine insulation state of health(SOh).

关键词： common-mode equivalent circuit machine decomposition machine stator winding insulation health model approximation

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Structure-function Aspects of Extracellular Leucine-rich Repeat-containing Cell Surface Receptors in Plants

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Journal of Integrative Plant Biology 2013年第12期55卷 1212-1223页

作者： zhao Zhang Bart P.h.J.Thomma Laboratory of Phytopathology Wageningen University Centre for BioSystems Genomics

Plants exploit several types of cell surface receptors for perception of extracellular signals, of which the extracellular leucine-rich repeat （eLRR）-containing receptors form the major class. Although the function of most plant eLRR receptors remains unclear, an increasing number of these receptors are shown to play roles in innate immunity and a wide variety of developmental processes. Recent efforts using domain swaps, gene shuffling analyses, site-directed mutagenesis, interaction studies, and crystallographic analyses resulted in the current knowledge on ligand binding and the mechanism of activation of plant eLRR receptors. This review provides an overview of eLRR receptor research, specificallysummarizing the recent understanding of interactions among plant eLRR receptors, their co-receptors and corresponding ligands. The functions of distinct eLRR receptor domains, and their role in structure, ligand perception and multimeric complex formation are discussed.

关键词： eLRR receptor-like kinase (RLK) receptor-like protein (RLP) pathogen-associated molecular pattern (PAMP) effector peptide ligand brassinosteroid CLE peptide.

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Application of kernel ridge regression in predicting neutron-capture reaction cross-sections

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Communications in Theoretical Physics 2022年第9期74卷 98-104页

作者： T X huang X h Wu P W zhao State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China

This article provides the first application of the machine-learning approach in the study of the cross-sections for neutron-capture reactions with the kernel ridge regression(KRR)*** is found that the KRR approach can reduce the root-mean-square(rms)deviation of the relative errors between the experimental data of the Maxwellian-averaged(n,γ)cross-sections and the corresponding theoretical predictions from 69.8%to 35.4%.By including the data with different temperatures in the training set,the rms deviation can be further significantly reduced to 2.0%.Moreover,the extrapolation performance of the KRR approach along different temperatures is found to be effective and reliable.

关键词： kernel ridge regression machine learning neutron-capture reaction

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