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Joint number and DOA estimation via the eigen-beam mCapon method for closely spaced sources

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Science China(Information Sciences) 2015年第12期58卷 217-219页

作者： GAO Yang XU jia jia xin Academy of Equipment School of Information and Electronics Beijing Institute of Technology

Dear editor,The source number and direction of arrival(DOA)estimation are two important subjects in array signal processing[1,2].Many algorithms for estimating these parameters have been proposed in the past

关键词： DOA Joint number and DOA estimation via the eigen-beam mCapon method for closely spaced sources MUSIC

Fractures interaction and propagation mechanism of multi-cluster fracturing on laminated shale oil reservoir

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Petroleum Science 2024年第4期21卷 2600-2613页

作者： jia-xin Lv Bing Hou Department of Petroleum Engineering China University of Petroleum(Beijing)at KaramayKaramay834000XinjiangChina Key Laboratory of Petroleum Engineering Ministry of EducationChina University of Petroleum(Beijing)Beijing102249China State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing102249China

The continental shale reservoirs of Jurassic Lianggaoshan Formation in Sichuan Basin contain thin lamina,which is characterized by strong plasticity and developed longitudinal shell limestone *** improve the production efficiency of reservoirs by multi-cluster fracturing,it is necessary to consider the unbalanced propagation of hydraulic fractures and the penetration effect of *** paper constructed a numerical model of multi-fracture propagation and penetration based on the finite element coupling cohesive zone method;considering the construction cluster spacing,pump rate,lamina strength and other parameters studied the influencing factors of multi-cluster fracture interaction propagation;combined with AE energy data and fracture mode reconstruction method,quantitatively characterized the comprehensive impact of the strength of thin interlayer rock interfaces on the initiation and propagation of fractures that penetrate layers,and accurately predicted the propagation pattern of hydraulic fractures through laminated shale oil *** results revealed that in the process of multi-cluster fracturing,the proportion of shear damage is low,and mainly occurs in bedding fractures activated by outer *** the cluster spacing enhances the fracture system's penetration ability,though it lowers the activation efficiency of *** high plasticity of the limestone interlayer may impact the vertical propagation distance of the main *** the interface strength is beneficial to the reconstruction of the fracture height,but the interface communication effect is *** selection of layers with moderate lamina strength for fracturing stimulation,increasing the pump rate during fracturing and setting the cluster spacing reasonably are beneficial to improve the effect of reservoir stimulation.

关键词： Laminated shale Multi-cluster fracturing Cross-layer Cohesive zone model Acoustic emission technique

Studies of a combined way of flame stability in ramjet combustor

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Defence Technology（防务技术） 2018年第5期14卷 441-445页

作者： jia-xin Tao Pump Equipment Research Center of Xi'an Aeronautical University Xi'an710077China

numerical simulation was conducted to study the influence of bleeding. The Euler-Lagrange method was used to investigate the two-phase turbulent combustion flow. Standard k-ε turbulent model was adopted in the continuous phase simulation and particle-trajectory model was adopted in the dispersed phase simulation. The results demonstrates: air bleeding can improve the flow field after the strut and the stability of trapped vortex in the cavity; change of bleeding temperature has little effect on the total pressure recovery coefficient and significant effect on combustion efficiency; When fuel-air ratio changes, the combustor performs better in a lean oil state.

关键词： Cavity Strut Bleeding Ramjet combustor Numerical simulation

Several fourth-order force gradient symplectic algorithms

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Research in Astronomy and Astrophysics 2010年第2期10卷 173-188页

作者： jia Xu xin Wu Department of Physics Nanchang University Nanchang 330031 China

By adding force gradient operators to symmetric compositions, we build a set of explicit fourth-order force gradient symplectic algorithms, including those of Chin and coworkers, for a separable Hamiltonian system with quadratic kinetic en- ergy T and potential energy V. They are extended to solve a gravitational n-body Hamiltonian system that can be split into a Keplerian part H0 and a perturbation part H1 in Jacobi coordinates. It is found that the accuracy of each gradient scheme is greatly superior to that of the standard fourth-order Forest-Ruth symplectic integra- tor in T ＋ V-type Hamiltonian decomposition, but they are both almost equivalent in the mean longitude and the relative position for H0 ＋//1-type decomposition. At the same time, there are no typical differences between the numerical performances of these gradient algorithms, either in the splitting of T ＋ V or in the splitting of H0 ＋//1. In particular, compared with the former decomposition, the latter can dra- matically improve the numerical accuracy. Because this extension provides a fast and high-precision method to simulate various orbital motions of n-body problems, it is worth recommending for practical computation.

关键词： celestial mechanics -- methods: numerical

Selection of raw materials and control of trace elements for production of high-quality SG iron

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China Foundry 2019年第2期16卷 79-87页

作者： jia-xin Bai China University of Geoscience Beijing

During the production of SG iron, the selection of raw materials and control of chemical composition are most important. From the very early days of SG iron production, the effects of trace elements on graphite form and matrix structure have been studied, and the allowable concentration limits for their detrimental influence has been decreased year by year, during the last fifty years. This paper has reviewed some of the suggested SG iron trace elements in the literature and in several Chinese foundries. It was found that for most SG iron castings, rare earth elements are still required to neutralize the harmful effects of trace elements and improve SG iron quality. It also found that the use of high purity and ultra-high purity base iron melts enabled integrated, safety-critical and complicated SG iron castings of varying thickness, and heavy-section, to be produced successfully. These SG iron castings have surprisingly good structures, and their mechanical and dynamic properties are vastly superior to those specified in current international SG iron standards. Further study is required on the effects of using high purity and ultra-high purity base melts on the structure and properties of SG iron.

关键词： trace elements anti-nodulizing and pearlite factors chunky graphite high and ultra-high purity pig iron high quality SG iron

甲烷在ZnO表面反应制合成气的微观机理研究

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原子与分子物理学报 2025年第6期42卷 1-9页

作者：黄琼谊楼波丁佳欣王水安华南理工大学电力学院广州510640

利用密度泛函(DFT)和过渡态理论对甲烷分子在ZnO表面的微观反应过程进行第一性原理研究,通过建立ZnO表面的吸附模型,计算了吸附能、过渡态参数和态密度,探讨了甲烷分子在氧化锌晶体表面H解离以及H_(2)和CO的生成过程,结果表明:CH_(4)在Z... 详细信息

利用密度泛函(DFT)和过渡态理论对甲烷分子在ZnO表面的微观反应过程进行第一性原理研究,通过建立ZnO表面的吸附模型,计算了吸附能、过渡态参数和态密度,探讨了甲烷分子在氧化锌晶体表面H解离以及H_(2)和CO的生成过程,结果表明:CH_(4)在ZnO(010)表面的最佳吸附位点为Zn位,吸附能为-4.65 kcal/mol,甲烷在氧化锌ZnO(010)面四次解离H(反应动力学上最有利路径)所需克服的能垒分别为38.6 kcal/mol、90.8 kcal/mol、53.2 kcal/mol和35.8 kcal/mol,其中甲烷第二次解离H_(2)过程能垒最高,是反应过程的决速步,降低该基元反应的活化能是关键,而-OH的形成抑制了-CH_(3)的解离.氧空位的形成增加活性位点的数量与提高位点的活性.甲烷与氧化锌表面的反应有两次H_(2)生成反应,第一次生成H_(2)的反应难度较大.

关键词：化学链重整甲烷反应机理密度泛函理论过渡态

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The differentiability of solutions for elliptic equations which degenerate on part of the boundary of a convex domain

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Applied Mathematics(A Journal of Chinese Universities) 2018年第4期33卷 421-435页

作者： SONG jia-xin CAO Yi Department of Mathematics and Information Science Shaanxi Normal University

In this paper,we study the differentiability of solutions on the boundary for equartions of type L;u=;u/x;+|x|;;u/y;=f（x,y）,where λ is an arbitrary positive number. By introducing a proper metric that is related to the elliptic operator L;, we prove the differentiability on the boundary when some well-posed boundary conditions are satisfied. The main difficulty is the construction of new barrier functions in this article.

关键词： elliptic equations convex domain differentiability

Biderivations of Hom-Lie Algebras and Superalgebras

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Acta Mathematica Sinica,English Series 2024年第10期40卷 2337-2358页

作者： La Mei YUAN jia xin LI School of Mathematics Harbin Institute of TechnologyHarbin 150001P.R.China

On Hom-Lie algebras and superalgebras,we introduce the notions of biderivations and linear commuting maps,and compute them for some typical Hom-Lie algebras and superalgebras,including the q-deformed W(2,2)algebra,the... 详细信息

关键词： Hom-Lie algebras biderivations linear commuting maps q-deformed W(2,2)algebra q-deformed Witt algebra q-deformed Witt superalgebra

Current status of drug therapy for chronic hepatitis B

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World Journal of Gastroenterology 2025年第2期31卷 1-12页

作者： Chuang jiang Zhi-Hong Zhang jia-xin Li Division of Liver Surgery Department of General Surgery and Laboratory of Liver Surgeryand State Key Laboratory of Biotherapy and Collaborative Innovation Center of BiotherapyWest China HospitalSichuan UniversityChengdu 610041Sichuan ProvinceChina Department of General Surgery Dafang County People's HospitalBijie 551600Guizhou ProvinceChina

In this editorial,we comment on the article by Meng et *** hepatitis B(CHB)is a significant global health problem,particularly in developing *** B virus(HBV)infection is one of the most important risk factors for cirrhosis and hepatocellular *** and treatment of HBV are key measures to reduce *** present,drug therapy can effectively control virus replication and slow disease progression,but completely eliminating the virus remains a ***-HBV treatment is a long-term process,and there are many kinds of antiviral drugs with different mechanisms of action,it is essential to evaluate the safety and efficacy of these drugs to reduce side effects and improve patients’*** will summarize the current status of CHB drug treatment,hoping to provide a reference for the selection of clinical antiviral drugs.

关键词： Chronic hepatitis B Hepatitis B virus Anti virus Drug treatment Therapy