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Doppler effect in high-speed rail seismic wavefield and its application

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Science China Earth Sciences 2022年第3期65卷 414-425页

作者： Yiran jiang Jieyuan ning Jingchong WEN Yongxiang SHI School of Earth and Space Sciences Peking UniversityBeijing 100871China Hongshan Geophysical National Observation and Research Station Beijing 100871China

We demonstrate by theoretical analysis that periodically distributed viaduct piers of high-speed rail result in the Doppler effect in the seismic wavefield of high-speed rail at specific frequencies and analyze the Doppler effect’s influence on the wavefield’s spectrum *** further verify our theoretical prediction by using observational data of the high-speed rail seismic wavefield in Rongcheng,Hebei Province,*** find that the wavefield component with a noticeable Doppler effect vibrates in the propagation direction and only has a unique apparent wave speed,indicating that P-wave is ***,we propose a speed measurement method based on the Doppler effect and measure the wave speed of the medium along the *** results are highly stable and consistent.

关键词： High-speed rail seismic wavefield Spectrum feature Doppler effect Doppler velocity measurement

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COMPUTER-AIDED BLOCK ASSEMBLY PROCESS PLANning IN SHIPBUILD-ING BASED ON RULE-REASOning

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Chinese Journal of Mechanical Engineering 2008年第2期21卷 99-103页

作者： ZHANG Zhiying LI zhen jiang Zhibin School of Mechanical Engineering Tongji University Shanghai 200092 China State Key Laboratory of Estuarine and Coastal Science East China Normal University Shanghai 200062 China School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200240 China

Computer-aided block assembly process planning based on rule-reasoning are developed in order to improve the assembly efficiency and implement the automated block assembly process planning generation in shipbuilding. First, weighted directed liaison graph （WDLG） is proposed to represent the model of block assembly process according to the characteristics of assembly relation, and edge list （EL） is used to describe assembly sequences. Shapes and assembly attributes of block parts are analyzed to determine the assembly position and matched parts of parts used frequently. Then, a series of assembly rules are generalized, and assembly sequences for block are obtained by means of rule reasoning. Final, a prototype system of computer-aided block assembly process planning is built. The system has been tested on actual block, and the results were found to be quite efficiency. Meanwhile, the fundament for the automation of block assembly process generation and integration with other systems is established.

关键词： Assembly process planning Rule reasoning Shipbuilding

Seabed Physical Parameter Research Based on Active-Source OBS Data in the Chukchi Sea Shelf of the Arctic

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Journal of Ocean University of China 2023年第3期22卷 675-682页

作者： zhen Sheng XING Junhui jiang Xiaodian Key Laboratory of Submarine Geosciences and Prospecting Techniques MOE and College of Marine GeosciencesOcean University of ChinaQingdao 266100China Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266071China

The acquisition of seabed physical parameters is one of the focuses of marine acoustic ***,the activesource ocean bottom seismometer(OBS)detection method in the marine geophysical research is rarely used to acquire seabed physical parameters,and less work is performed in the *** this study,two active-source OBS data collected from the 9th and 11th Chinese National Arctic Research Expedition(CHINARE)are selected to obtain the physical parameters of seabed *** kinds of energy spark are used as the active sources,while the cost function inversion method is used based on the arrival time difference between the reflected and direct *** thickness and sound velocity of the sediment layers are obtained by inversion,and the empirical formula is used to calculate the physical parameters of the seabed sediment,which are compared with the measured *** cost function inversion method based on the time difference of arrival of the reflected and direct waves is tested to be effective and feasible in the inversion of seabed parameters from active-source OBS *** method is further applied to obtain the physical parameters of Chukchi seabed sediments,which provides the idea and reference for the application of marine geophysical activesource OBS detection technology in the inversion of polar seabed physical parameters.

关键词： physical parameters of seafloor sediments ocean bottom seismometer(OBS) Arctic Chukchi Sea

Effect of reduction pretreatment process on evolution of micro-porosity in 42CrMo billet

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Journal of Iron and Steel Research International 2021年第4期28卷 413-423页

作者： zhen ning Wei Yu Hong-qiang Liu Qing-wu Cai Collaborative Innovation Centre of Steel Technology University of Science and Technology BeijingBeijing 100083China HBIS Group Co. Ltd.Shijiazhuang 050000HebeiChina

Reduction pretreatment(RP)process,which is implemented after the billet is completely solidified,is an alternative process to further improve billet *** element method and experiment were used to investigate the effect of the RP process on the internal quality of 42CrMo *** ultrasonic testing technology was used to study the influence of the RP process on the *** a three-dimensional finite element model,the mechanism of the RP process on the porosity closure was *** experimental results show that the RP process eliminates the macro-porosities of the billet *** number of micro-porosities in the billets is effectively reduced,and the increase in deformation contributes to the reduction in *** with isothermal rolling,the RP process leads to a larger equivalent strain and hydrostatic integration in the billet center because of the temperature gradient,and the effect of the temperature gradient is greater with the increase in *** closure effect of micro-porosity is related not only to the stress state,but also to the distribution of *** increase in three-dimensional compressive stress is beneficial to the porosity *** the micro-porosities distributed densely,excessive stress could induce micro-porosity coalescence,which has the risk of inducing cracks.

关键词： Reduction pretreatment Temperature gradient Large deformation Micro-porosity Ultrasonic testing

Effects of Sequence Distribution and Physical Aging on Physical Properties of PES/PEES Random, Block, and Alternative Copolymers

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Chemical Research in Chinese Universities 2006年第6期22卷 787-791页

作者： ZHOU Xiao-ming jiang zhen-hua Alan G. MacDiarmid Lab College of Chemistry Jilin University Changchun 130012 P. R. China

The random, block, and alternative copolymers of poly ether sulfone（PES） and poly ether ether sulfone（PEES） were synthesized v/a three kinds of methods. The chemical structures of the three kinds of copolymers were characterized by ^13C NMR. Three kinds of PES/PEES copolymers（ Tg =215 ℃ ）, which were almost identical in composition but different in sequence distribution, were used. Their physical aging process was studied by differential scanning calorimetry（DSC） at three aging temperatures ranging between Tg -15 ℃ and Tg -25℃. The experimental results reveal that the alternative copolymer shows a lower enthalpy relaxation time 〈T〉 and apparent activation energy when compared with the random and block copolymers. The result of the electron-microscopy investigation of the three copolymers that were treated at 200 ℃ for 96 h indicates that the molecular aggregation of the copolymers changed from a randomly coiled amorphous phase to an ordered phase, and the ordered structure of the alternative copolymer was more distinct than that of the random phase. The experimental results of this study suggest that the motion of the sagments is affected by the different molecular-chain sequence distribution.

关键词： Physical aging Apparent activation energy Sequence distribution

Left ventricular thrombosis caused cerebral embolism during venoarterial extracorporeal membrane oxygenation support: A case report

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World Journal of Clinical Cases 2024年第5期12卷 973-979页

作者： Yao-Bang Bai Feng Zhao zhen-Hua Wu Guo-ning Shi Nan jiang Intensive Care Unit Department of Cardiac SurgeryTianjin Chest HospitalTianjin 300222China Department of Cardiac Surgery Tianjin Chest HospitalTianjin 300222China

BACKGROUND Venoarterial(VA)extracorporeal membrane oxygenation(ECMO),an effective short-term circulatory support method for refractory cardiogenic shock,is widely ***,retrospective analyses have shown that VA-ECMO-assisted cases were associated with a relatively high mortality rate of approximately 60%.Embolization in important organs caused by complications of left ventricular thrombosis(LVT)during VA-ECMO is also an important *** the incidence of LVT during VA-ECMO is not high,the consequences of embolization are *** SUMMARY A 37-year-old female patient was admitted to hospital because of fever for 4 d and palpitations for 3 *** excluding the diagnosis of coronary heart disease,we established a diagnosis of“clinically explosive myocarditis”.The patient still had unstable hemodynamics after drug treatment supported by VA-ECMO,with heparin for *** day 4 of ECMO support,a left ventricular thro-mbus attached to the papillary muscle root of the mitral valve was found by transthoracic *** ventricular decompression was performed and ECMO was successfully removed,but the patient eventually died of multiple cerebral *** LVT with high mobility during VA-ECMO may cause embolism in important ***,a"wait and see"strategy should be avoided.

关键词： Venoarterial extracorporeal membrane oxygenation Left ventricular thrombosis Cerebral embolism Magnetic Resonance Imaging Therapy Case report

Recent progress on the activation of the cGAS–STING pathway and its regulation by biomolecular condensation

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Journal of Molecular Cell Biology 2022年第6期14卷 1-13页

作者： Xiaoyu Yu zhen Zhao zhengfan jiang Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education School of Life SciencesPeking UniversityBeĳing 100871China Peking-Tsinghua Center for Life Sciences Peking UniversityBeĳing 100871China

The cyclic guanosine monophosphate (GMP)–adenosine monophosphate (AMP) synthetase (cGAS)–stimulator of interferon genes(STING) pathway, comprising the DNA sensor cGAS, the second messenger cyclic GMP–AMP (cGAMP), and the endoplasmicreticulum (ER) adaptor protein STING, detects cytoplasmic double-stranded DNA (dsDNA) to trigger type I-interferon responses forhost defense against pathogens. Previous studies defined a model for the allosteric activation of cGAS by DNA-binding, but recentwork reveals other layers of mechanisms to regulate cGAS activation such as the phase condensation and metal ions, especially thediscovery of Mn^(2+) as a cGAS activator. Activation of the 23-cGAMP sensor STING requires translocating from the ER to the Golgiapparatus. The sulfated glycosaminoglycans at the Golgi are found to be the second STING ligand promoting STING oligomerizationand activation in addition to 23-cGAMP, while surpassed levels of 23-cGAMP induce ER-located STING to form a highly organizedER membranous condensate named STING phase-separator to restrain STING activation. Here, we summarize recent advances in theregulation of cGAS–STING activation and their implications in physiological or pathological conditions, particularly focusing on theemerging complexity of the regulation.

关键词： innate immunity cGAS-STING cGAMP manganese(Mn2+) sulfated glycosaminoglycans(sGAGs) biomolecular condensate STING phase-separator

WAVEFORM RELAXATION METHODS FOR LIE-GROUP EQUATIONS

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Journal of Computational Mathematics 2022年第4期40卷 649-666页

作者： Yaolin jiang zhen Miao Yi Lu School of Mathematics and Statistics Xi’an Jiaotong UniversityXi’an 710049China

In this paper,we derive and analyse waveform relaxation(WR)methods for solving differential equations evolving on a *** present both continuous-time and discrete-time WR methods and study their convergence *** the discrete-time case,the novel methods are constructed by combining WR methods with Runge-KuttaMunthe-Kaas(RK-MK)*** obtained methods have both advantages of WR methods and RK-MK methods,which simplify the computation by decoupling strategy and preserve the numerical solution of Lie-group equations on a *** numerical experiments are given to illustrate the feasibility of the new WR methods.

关键词： Lie-group equations Waveform relaxation RK-MK methods Convergence analysis

Implicit high-order discontinuous Galerkin method with HWENO type limiters for steady viscous flow simulations

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Acta Mechanica Sinica 2013年第4期29卷 526-533页

作者： zhen-Hua jiang Chao Yan Jian Yu College of Aeronautics Science and Engineering Beijing University of Aeronautics and Astronautics

Two types of implicit algorithms have been im- proved for high order discontinuous Galerkin （DG） method to solve compressible Navier-Stokes （NS） equations on tri- angular grids. A block lower-upper symmetric Gauss- Seidel （BLU-SGS） approach is implemented as a nonlin- ear iterative scheme. And a modified LU-SGS （LLU-SGS） approach is suggested to reduce the memory requirements while retain the good convergence performance of the origi- nal LU-SGS approach. Both implicit schemes have the sig- nificant advantage that only the diagonal block matrix is stored. The resulting implicit high-order DG methods are applied, in combination with Hermite weighted essentially non-oscillatory （HWENO） limiters, to solve viscous flow problems. Numerical results demonstrate that the present implicit methods are able to achieve significant efficiency improvements over explicit counterparts and for viscous flows with shocks, and the HWENO limiters can be used to achieve the desired essentially non-oscillatory shock tran- sition and the designed high-order accuracy simultaneously.

关键词： Discontinuous Galerkin (DG) scheme ~ Implicitmethod ~ HWENO ~ High order ~ Unstructured grids