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Effect of dimensionless heat input during laser solid forming of high-strength steel

Journal of Materials Science & Technology 2022年第4期99卷 127-137页

作者： Chunping Huang Renyu Liang Fenggang Liu Haiou Yang Xin Lin National Defense Key Discipline Laboratory of Light Alloy Processing Science and Technology Nanchang Hangkong UniversityNanchang 330063China Key Laboratory of Metal High Performance Additive Manufacturing and Innovative Design MIIT ChinaNorthwestern Polytechnical UniversityXi’an 710072China

Laser solid forming(LSF)technology can be used to rapidly manufacture and repair high-strength steel parts with superior performance,but the value of the heat input during operation is difficult to quantify,which has a substantial impact on the microstructure and mechanical properties of the parts.A promising method to improve the forming efficiency and quality of LSFed parts is to accurately control the heat input and explore its relationship with the microstructure and mechanical properties.To remove the interference of other variables from the experiment,the dimensionless heat input Q;^(∗)was introduced.The Q^(∗)values were designed in advance to calculate the experimental parameters used to perform the LSF experiment.The microstructure was observed at different regions of the sample,and its mechanical properties were analyzed.From the results,the following conclusions were drawn.The Q;^(∗)value was directly related to the cooling rate and heat accumulation in the top structure,leading to the formation of different microstructures;it also modified the original structure at the bottom,affecting the subsequent thermal cycle and indirectly changing the tempered martensite morphology.The heat input also affected the mechanical properties of the sample.The hardness of the stable zone decreased with increasing Q;^(∗)value,and the lowest value was 190 HV.Similarly,the tensile strength and yield strength of the LSFed samples decreased considerably with increasing Q;^(∗)value,and the lowest values were 735 and 604 MPa,respectively.Only the elongation and reduction in the area increased after a slight decrease.The Q;^(∗)value had a significant effect on heat treatment.When Q;^(∗)=2.9,the increase in tensile strength and yield strength after heat treatment was the largest(29%and 44%,respectively).

关键词： Dimensionless heat input Laser solid forming High-strength steel Microstructure Mechanical property

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Experimental and Numerical Analysis of Particle Migration and Patterning Behavior in a Gravel Pack

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Fluid Dynamics & Materials Processing 2023年第4期19卷 911-928页

作者： Bobo Luo Yunbin Xiong Zhuoyi Li Zhanqing Qu Fenggang Liu Tiankui Guo Zugui Yang Yina Shi Exploration and Development Research Institute Zhongyuan Oilfield CompanySINOPECPuyangChina The University of Manchester ManchesterUK College of Petroleum Engineering China University of Petroleum(East China)QingdaoChina

Due to its long lifespan and high sand-removal efficiency,gravel packing is one of the most applied sand control methods during the recovery of reservoirs with sanding problems.The blockage and retention of injected sand in a gravel pack is a complex process affected by multiple mechanisms.The majority of existing studies based on the phenomenological deep bed filtration(DBF)theory focused on the gravel pack’s overall permeability damage and failed to obtain the inner-pore particle distribution pattern.In this work,experiments and simulations were carried out to reveal the particle distribution in a gravel pack during flooding.In particular,through real-time monitoring of particle migration,the penetration depth and distribution pattern of invaded particles with different gravel-sand particle ratios,fluid viscosities and injection rates could be determined.By simplifying each unit bed element(UBE)into a pore-throat structure with four tunnels(two horizontals for discharge and two verticals for sedimentation),a new network simulation method,which combines deep bed filtration with a particle trajectory model,was implemented.Cross comparison of experimental and numerical results demonstrates the validity and accuracy of the model.

关键词： Gravel pack sand control deep bed filtration visual experiment particle trajectory

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Closed-form algorithms for computing the intersection of two subspaces

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Journal of Systems Engineering and Electronics 2019年第2期30卷 245-250页

作者： YAN fenggang liu Shuai WANG Jun JIN Ming School of Information Science and Engineering Harbin Institute of Technology at Weihai

Finding the intersection of two subspaces is of great interest in many fields of signal processing. Over several decades,there have been numerous formulas discovered to solve this problem, among which the alternate projection method(APM) is the most popular one. However, APM suffers from high computational complexity, especially for real-time applications. Moreover, APM only gives the projection instead of the orthogonal basis of two given subspaces. This paper presents two alternate algorithms which have a closed form and reduced complexity as compared to the APM technique. Numerical simulations are conducted to verify the correctness and the effectiveness of the proposed methods.

关键词： orthogonal projection singular value decomposition alternate projection method (APM) intersection

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Fast and accurate covariance matrix reconstruction for adaptive beamforming using Gauss-Legendre quadrature

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Journal of Systems Engineering and Electronics 2021年第1期32卷 38-43页

作者： liu Shuai ZHANG Xue YAN fenggang WANG Jun JIN Ming School of Information Science and Engineering Harbin Institute of TechnologyWeihai 264209China

Most of the reconstruction-based robust adaptive beamforming(RAB)algorithms require the covariance matrix reconstruction(CMR)by high-complexity integral computation.A Gauss-Legendre quadrature(GLQ)method with the highest algebraic precision in the interpolation-type quadrature is proposed to reduce the complexity.The interference angular sector in RAB is regarded as the GLQ integral range,and the zeros of the threeorder Legendre orthogonal polynomial is selected as the GLQ nodes.Consequently,the CMR can be efficiently obtained by simple summation with respect to the three GLQ nodes without integral.The new method has significantly reduced the complexity as compared to most state-of-the-art reconstruction-based RAB techniques,and it is able to provide the similar performance close to the optimal.These advantages are verified by numerical simulations.

关键词： robust adaptive beamforming(RAB) covariance matrix reconstruction(CMR) Gauss-Legendre quadrature(GLQ) complexity reduction

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SVD-Based Low-Complexity Methods for Computing the Intersection of K≥2 Subspaces

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Chinese Journal of Electronics 2019年第2期28卷 430-436页

作者： YAN fenggang WANG Jun liu Shuai JIN Ming SHEN Yi School of Information and Electrical Engineering Harbin Institute of Technology at Weihai School of Astronautics Harbin Institute of Technology

Given the orthogonal basis(or the projections) of no less than two subspaces in finite dimensional spaces, we propose two novel algorithms for computing the intersection of those subspaces. By constructing two matrices using cumulative multiplication and cumulative sum of those projections, respectively, we prove that the intersection equals to the null spaces of the two matrices. Based on such a mathematical fact,we show that the orthogonal basis of the intersection can be efficiently computed by performing singular value decompositions on the two matrices with much lower complexity than most state-of-the-art methods including alternate projection method. Numerical simulations are conducted to verify the correctness and the effectiveness of the proposed methods.

关键词： Orthogonal projection Cumulative sum Cumulative multiplication Singular value decomposition Intersection

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Low-degree root-MUSIC algorithm for fast DOA estimation based on variable substitution technique

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Science China(Information Sciences) 2020年第5期63卷 218-220页

作者： fenggang YAN Ming JIN Hongjuan ZHOU Jun WANG Shuai liu School of Information Science and Engineering Harbin Institute of Technology at Weihai

Dear editor,U-root-MUSIC [1] is one of the most popular unitary direction of arrival (DOA) estimation methods [2], and its eigenvalue decomposition (EVD)stage involves only real-valued (RV) arithmetic.Recently, a version of RV-root-MUSIC, which allows RV computations for both EVD and polynomial rooting, was reported in [3]. Nevertheless,the RV-root-MUSIC polynomial is of a high de-

关键词： Low-degree root-MUSIC algorithm for fast DOA estimation based on variable substitution technique DOA

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Joint polarization and DOA estimation based on improved maximum likelihood estimator and performance analysis for conformal array

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Journal of Systems Engineering and Electronics 2023年第6期34卷 1490-1500页

作者： SUN Shili liu Shuai WANG Jun YAN fenggang JIN Ming School of Information Science and Engineering Harbin Institute of TechnologyWeihai 264209China

The conformal array can make full use of the aperture,save space,meet the requirements of aerodynamics,and is sensitive to polarization information.It has broad application prospects in military,aerospace,and communication fields.The joint polarization and direction-of-arrival(DOA)estimation based on the conformal array and the theoretical analysis of its parameter estimation performance are the key factors to promote the engineering application of the conformal array.To solve these problems,this paper establishes the wave field signal model of the conformal array.Then,for the case of a single target,the cost function of the maximum likelihood(ML)estimator is rewritten with Rayleigh quotient from a problem of maximizing the ratio of quadratic forms into those of minimizing quadratic forms.On this basis,rapid parameter estimation is achieved with the idea of manifold separation technology(MST).Compared with the modified variable projection(MVP)algorithm,it reduces the computational complexity and improves the parameter estimation performance.Meanwhile,the MST is used to solve the partial derivative of the steering vector.Then,the theoretical performance of ML,the multiple signal classification(MUSIC)estimator and Cramer-Rao bound(CRB)based on the conformal array are derived respectively,which provides theoretical foundation for the engineering application of the conformal array.Finally,the simulation experiment verifies the effectiveness of the proposed method.

关键词： conformal array maximum likelihood(ML)estimator manifold separation technology(MST) parameter estimation Cramer-Rao bound(CRB).

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PEI/Zr4+-coated nanopore for detection of ochratoxin A

PEI/Zr4+-coated nanopore for detection of ochratoxin A

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中国化学会第十三届全国分析化学年会

作者： Fenggang Liu Shujie Chen Yuqing Chen Jiahai Wang School of Chemistry and Chemical Engineering Guangzhou University

我们开发了一种新型基于仿生纳米孔和单碳纳米管检测赭曲霉素A (OTA)的方法,与常规方法相比,本方法不需要针对纳米孔进行表面修饰特异性探针。我们通过静电作用,在对称的纳米孔上修饰聚乙烯亚胺(PEI)和Zr,进而达到定量测定OTA含量的目的... 详细信息

我们开发了一种新型基于仿生纳米孔和单碳纳米管检测赭曲霉素A (OTA)的方法,与常规方法相比,本方法不需要针对纳米孔进行表面修饰特异性探针。我们通过静电作用,在对称的纳米孔上修饰聚乙烯亚胺(PEI)和Zr,进而达到定量测定OTA含量的目的:适配体-OTA复合物可以通过Zr-PO相互作用容易地积累在纳米孔表面上,而其他游离适体则被单壁碳纳米管(SWNTs)去除。纳米孔传感器的检测限为28.6nM,线性范围为10 nM至3 μM。该纳米孔传感器显示出对其他赭曲霉毒素A类似物如NAP和华法林的优异选择性。

关键词：纳米孔赭曲霉毒素A 单壁碳纳米管锆离子

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Achieving excellent electro-optic activity and thermal stability in monolithic cross-linked nonlinear optical dendrimers

Achieving excellent electro-optic activity and thermal stabi...

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中国化学会第十三届全国分析化学年会

作者： Fenggang Liu Shujie Chen Yuqing Chen Jiahai Wang School of Chemistry and Chemical Engineering Guangzhou University

我们研发两个新颖的含蒽或丙烯酸酯功能化基团的的非线性光学树枝状发色团,以有效提高有机电光材料的极化效率和热稳定性。这些以四烯为桥的新型树枝状大分子最初具有相对低的玻璃化转变温度,在加热极化后可以形成发色团网络从而提高电... 详细信息

我们研发两个新颖的含蒽或丙烯酸酯功能化基团的的非线性光学树枝状发色团,以有效提高有机电光材料的极化效率和热稳定性。这些以四烯为桥的新型树枝状大分子最初具有相对低的玻璃化转变温度,在加热极化后可以形成发色团网络从而提高电光材料的热稳定性和提供有效的位阻。在极化取向之后,由于发色团含量的有效增加,这些树枝状聚合物在1310nm下获得了210pm/V超大的电光系数。极化后的电光树枝状分子可以在200℃下保持电光系数稳定性30分钟,并且在150℃下具有长达超过300小时的稳定性。这些都为超大电光系数、超稳的电光调制器的制备提供了可能。

关键词：发色团交联树枝状分子电光系数

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Cooling of double crystal monochromator with sagittal focus at SSRF

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Nuclear Science and Techniques 2010年第2期21卷 65-68页

作者： WANG Naxiu liu Shilei XU Zhongmin BIAN fenggang Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201204 China Graduate University of Chinese Academy of Sciences Beijing 10049 China

In SSRF, the design of 1st crystal cooling geometry of double crystal monochromator with sagittal focus is mainly reported by China. Our simulation indicates that the broadening of the full width at half maximum of the rocking curve of the double crystal monochromator induced by the heat load is about 3.7 μrad, and is in agreement with the experimental value of 5 μrad. Our scheme showed that the photon flux is reliably linear with electron current of the storage ring, which is extracted from the monochromator.

关键词：晶体单色器光源上海双晶聚焦冷却电子储存环几何形状

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