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Finite-difference modeling of Maxwell viscoelastic media developed from perfectly matched layer

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Petroleum Science 2023年第5期20卷 2759-2772页

作者： Ruo-long Song College of Physics Jilin UniversityChangchun130012JilinChina

In numerical simulation of wave propagation,both viscoelastic materials and perfectly matched layers(PMLs)attenuate *** wave equations for both the viscoelastic model and the PML contain convolution ***,convolution operator is intractable in finite-difference time-domain(FDTD)method.A great deal of progress has been made in using time stepping instead of convolution in *** incorporate PML into viscoelastic media,more memory variables need to be introduced,which increases the code complexity and computation *** modifying the nonsplitting PML formulation,I propose a viscoelastic model,which can be used as a viscoelastic material and/or a PML just by adjusting the *** proposed viscoelastic model is essentially equivalent to a Maxwell *** with existing PML methods,the proposed method requires less memory and its implementation in existing finite-difference codes is much *** attenuation and phase velocity of P-and S-waves are frequency independent in the viscoelastic model if the related quality factors(Q)are greater than *** numerical examples show that the method is stable for materials with high absorption(Q=1),and for heterogeneous media with large contrast of acoustic impedance and large contrast of viscosity.

关键词： Finite difference Viscoelastic model Nonsplitting perfectly matched layer

Conjugate Heat Transfer for Free Convection along a Vertical Plate Fin

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journal of Thermal Science 2010年第4期19卷 337-345页

作者： Kai-long Hsiao Department of Digital Entertainment and Game Design Diwan University

In this study,a new and effective improved Semi-Analytic and Semi-Empirical formula f(Pr)= (0.749999437Pr^(1/2))/((0.609+1.221Pr^(1/2)+1.238Pr)^(1/4))has been proposed to solve a conjugate problem with free convection in the incompressible laminar boundary layer flow and heat conduction in a solid wall for the flow passing a flat plate fin. A combination of flat-plate flow and flat-plate fin heat conduction has been considered in the present *** -difference solutions for the interface temperature profiles and the heat transfer rates have been presented over the entire thermo-fluid-dynamic field for Prandtl numbers from 0.001 to ***,the similar flow field has been solved by the Runge-Kutta method and the shooting methods,then the correlation equation of the local heat transfer coefficient have been ***,the empirical formula has been substituted into the fin temperature heat conduction calculation processes to obtain the iterative solutions of the conjugate problems.

关键词： Conjugate heat transfer Free convection Vertical plate fin Finite difference Runge-Kutta method Shooting method.

Editorial:Secure and Safe Meta Control for Cyber Physical Systems

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IEEE/CAA journal of Automatica Sinica 2023年第12期10卷 2177-2178页

作者： Qing-long Han IEEE the School of Science Computing and Engineering TechnologiesSwinburne University of TechnologyMelbourneVIC 3122Australia

welcome to the twelfth issue of 2023 in the IEEE/CAA journal of Automatica Sinica(jAS).In the sixth issue of2023,I systematically addressed the latest development of Meta Vehicles,and sorted out some important contributions published in the IEEE/CAA jAS focusing on control,estimation,and optimization of automated vehicles with reliability,security,efficiency,and intelligence.

关键词： Secure automated estimation

SYNTHESIS OF AN EPOXY-TERMINATED HYPERBRANCHED AROMATIC POLYESTER

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Chinese journal of Polymer Science 2002年第6期20卷 585-590页

作者： w.j.Feast IRC in Polymer Science and Technology Durham University South Road Durham DH1 3LE UK

An epoxy-terminated hyperbranched aromatic polyester (P3) was synthesized from a hyperbranched aromatic polyester containing carboxylic acid end groups (P1), which was derived from the condensation polymerization of the AB(2) monomer, 5-acetoxyisophthalic acid. Polymer P1 was converted into the polymeric acid chloride by reaction with thionyl chloride. The acid chloride was reacted with ethanol and glycidol to form a poly(ethyl ester) (P2) and an epoxy terminated material (P3), respectively. The reaction conditions in each step of these processes had to be controlled very carefully to avoid unwanted cross-linking reactions. The characterization of products and intermediates, including molecular weight distributions and thermal properties, are reported.

关键词： hyperbranched polymer hyperbranched aromatic polyester epoxy-terminated hyperbranched aromatic polyester

An Introduction to Advanced Hot-Formed Steel for Automobile

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Acta Metallurgica Sinica(English Letters) 2014年第3期27卷 373-382页

作者： w.j.Liu Research Academy Northeastern University

A recently developed advanced hot-formed （AHF） steel for automobile is introduced and three physical metallurgy concepts based on which the AHF steel was designed are reviewed, they are dynamic carbon partitioning （DCP）, flash copper precipitation and bake toughening. AHF steel is an upgrade of the existing hot-formed steel especially suitable for making components with superior crashworthiness; it can be processed by regular hot stamping equipment and process. A kinetics model for DCP is expressed in detail, which can be used to calculate the volume fraction of retained austenite based on four materials and processing parameters. The flash copper precipitation used as an additional strengthening mechanism for AHF steel is also discussed and its ultrafast kinetics can be attributed to the enhancement of quenched-in vacancies on copper diffusion. Also, the bake toughening of AHF steel is addressed; the mechanism of which may be related to the elimination of the less stable block-like retained austenite.

关键词： Advanced hot-formed (AHF) steel Dynamic carbon partitioning Flash copper precipitation Bake toughening Hot stamping

The role of endoscopy in the management of hereditary diffuse gastric cancer syndrome

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world journal of Gastroenterology 2019年第23期25卷 2878-2886页

作者： Shria Kumar jessica M long Gregory G Ginsberg Bryson w Katona Division of Gastroenterology University of Pennsylvania Perelman School of MedicinePhiladelphiaPA 19104United States Division of Hematology and Oncology University of Pennsylvania Perelman School of MedicinePhiladelphiaPA 19104United States

Hereditary diffuse gastric cancer(HDGC) syndrome is an inherited cancer risk syndrome associated with path-ogenic germline CDH1 variants. Given the high risk for developing diffuse gastric cancer, CDH1 carriers are recommended to undergo prophylactic total gastrectomy for cancer risk reduction. Current guidelines recommend upper endoscopy in CDH1 carriers prior to surgery and then annually for individuals deferring prophylactic total *** of individuals from HDGC families without CDH1 pathogenic variants remains less clear, and management of families with CDH1 pathogenic variants in the absence of a family history of gastric cancer is particularly problematic at present. Despite adherence to surveillance protocols, endoscopic detection of cancer foci in HDGC is suboptimal and imperfect for facilitating decision-making. Alternative endoscopic modalities, such as chromoendoscopy,endoscopic ultrasound, and other non-white light methods have been utilized,but are of limited utility to further improve cancer detection and risk stratification in HDGC. Herein, we review what is known and what remains unclear about endoscopic surveillance for HDGC, among individuals with and without germline CDH1 pathogenic variants. Ultimately, the use of endoscopy in the management of HDGC remains a challenging arena, but one in which further research to improve surveillance is crucial.

关键词： CDH1 gene Hereditary diffuse gastric cancer Gastric cancer Endoscopic screening Endoscopy

Latest research progress for LBE coolant reactor of China initiative accelerator driven system project

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Frontiers in Energy 2021年第4期15卷 810-831页

作者： long GU Xingkang SU Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China

China’s accelerator driven subcritical system(ADS)development has made significant progress during the past *** the successful construction and operation of the international prototype of ADS superconducting proton linac,the lead-based critical/subcritical zero-power facility VENUS-II and the comprehensive thermal-hydraulic and material test facilities for LBE(lead bismuth eutectic)coolant,China is playing a pivotal role in advanced steady-state operations toward the next step,the ADS *** China initiative Accelerator Driven System(CiADS)is the next facility for China’s ADS program,aimed to bridge the gaps between the ADS experiment and the LBE cooled subcritical *** total power of the CiADS will reach 10 *** CiADS engineering design was approved by Chinese government in *** then,the CiADS project has been fully transferred to the construction application *** subcritical reactor is an important part of the whole CiADS ***,a pool-type LBE cooled fast reactor is chosen as the subcritical reactor of the *** and thermal experiments and software development for LBE coolant were conducted simultaneously to support the design and construction of the CiADS LBEcooled subcritical ***,it is necessary to introduce the efforts made in China in the LBE-cooled fast reactor to provide certain supporting data and reference solutions for further design and development for ***,the roadmap of China’s ADS,the development process of the CiADS,the important design of the current CiADS subcritical reactor,and the efforts to build the LBE-cooled fast reactor are presented.

关键词： LBE(lead bismuth eutectic)coolant reactor China initiative Accelerator Driven System(CiADS)project research progress

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水下舰艇扩频通信体制研究

现代电子技术 2025年第1期48卷 107-111页

作者：李尧赵健康龙海辉上海交通大学电子信息与电气工程学院上海200240

水下舰艇通信采用的水声通信方式在长距离传输中信号衰减严重,且因为隐蔽性需求信号功率受限,叠加受到多径干扰和海洋背景噪声干扰,通信误码率较高。为此,提出水下舰艇扩频通信体制研究。设计扩频通信体制,利用扩频通信体制拓宽传输带宽... 详细信息

水下舰艇通信采用的水声通信方式在长距离传输中信号衰减严重,且因为隐蔽性需求信号功率受限,叠加受到多径干扰和海洋背景噪声干扰,通信误码率较高。为此,提出水下舰艇扩频通信体制研究。设计扩频通信体制,利用扩频通信体制拓宽传输带宽,提升远距离衰减下的通信信噪比;采用类白噪声的伪随机码m序列和OPS序列作为扩频码组建编码序列集,解决白噪声干扰、多径干扰和码分多址的问题。测试结果表明:同等条件下,采用m序列的扩频通信结果更优,可以实现-25 dB下误码率低于1%的可靠通信。经过该方法调制后,剔除了噪声干扰和多径干扰,增强了衰减的高频信号,解决了水下通信远距离衰减、多径干扰、背景噪声干扰等问题。

关键词：水下舰艇通信扩频通信 m序列 OPS序列误码率信噪比

Photocatalytic activation of sulfite by N-doped porous biochar/MnFe_(2)O_(4) interface-driven catalyst for efficient degradation of tetracycline

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Green Energy & Environment 2024年第3期9卷 481-494页

作者： long Cheng Yuanhui ji jiangsu Province Hi-Tech Key Laboratory for Biomedical Research School of Chemistry and Chemical EngineeringSoutheast UniversityNanjing211189China

A novel photo-catalytic system composed of N-doped biochars(NBCs),MnFe_(2)O_(4) and sulfite activation under ultraviolet(NBCs/MnFe_(2)O_(4)/sulfite/UV)was constructed to realize the efficient eliminate of tetracycline(TC).As the carrier of MnFe_(2)O_(4),NBCs were synthesized from alfalfa,which has large specific surface area,graphite like structure and hierarchical porous *** adsorption isotherm indicated that NBCs/MnFe_(2)O_(4)-2:1 had the best adsorption performance for TC(347.56 mg g^(-1)).Through synergistic adsorption and photocatalysis,the removal rate of TC reached 84%,which was significantly higher than that of MnFe_(2)O_(4).Electrochemical impedance spectroscopy(EIS)and Photoluminescence(PL)characterization results showed that the introduction of NBCs improved the separation efficiency of photogenerated electron and hole pairs and enhanced the photocatalytic ***,the adsorption,degradation mechanism and degradation path of TC by the catalyst were systematically analyzed by coupling HPLC–MS measurement with the theoretical *** the advantages of excellent degradation performance,low cost,easy separation and environmental friendliness of NBCs/MnFe_(2)O_(4),this work was expected to provide a new path for the practical application of biochar.

关键词： Biochar MnFe_(2)O_(4) Sulfite Adsorption Photocatalysis