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Influence of Shear Effects on the Characteristics of Axisymmetric Wave Propagation in a Buried Fluid‑Filled Pipe

Chinese Journal of Mechanical Engineering 2022年第3期35卷 275-284页

作者： Ping lu Xiaozhen sheng Yan Gao Ruichen Wang State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610031China School of Urban Railway Transportation Shanghai University of Engineering ScienceShanghai 201620China Key Laboratory of Noise and Vibration Research Institute of AcousticsChinese Academy of SciencesBeijing 100190China Institute of Railway Research University of HuddersfieldHuddersfield HD13DHUK

The acoustic propagation characteristics of axisymmetric waves have been widely used in leak detection of fluid-filled *** related acoustic methods and equipment are gradually coming to the market,but their theoretical research obviously lags behind the field practice,which seriously restricts the breakthrough and innovation of this *** on the fully three-dimensional effect of the surrounding medium,a coupled motion equation of axisymmetric wave of buried liquid-filled pipes is derived in detail,a contact coefficient is used to express the coupling strength between surrounding medium and pipe,then,a general equation of motion was derived which contain the pipe soil lubrication contact,pipe soil compact contact and pipe in water and ***,the corresponding numerical calculation model is established and solved used numerical *** shear effects of the surrounding medium and the shear effects at the interface between surrounding medium and pipe are discussed in *** output indicates that the surrounding medium is to add mass to the pipe wall,but the shear effect is to add *** the consideration of the contact strength between the pipe and the medium,the additional mass and the pipe wall will resonate at a specific frequency,resulting in a significant increase in the radiation wave to the surrounding *** research contents have great guiding effect on the theory of acoustic wave propagation and the engineering application of leak detection technology in the buried pipe.

关键词： Buried fluid-filled pipe Axisymmetric waves Shear effect Dispersion

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Genetic and clinical markers for predicting treatment responsiveness in rheumatoid arthritis

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Frontiers of Medicine 2019年第4期13卷 411-419页

作者： Xin Wu Xiaobao sheng Rong sheng Hongjuan lu Huji Xu Department of Rheumatology and Immunology Shanghai Changzheng Hospital the Second Military Medical University Shanghai 200003 China School ofEconomics and Management Tongji University Shanghai 200092 China The Third Research Institute of the Ministry of Public Security Shanghai 200031 China Beijing Tsinghua Changgung Hospital School of Clinical Medicine Tsinghua University Beijing 100084 China Peking-Tsingh ua Center for Life Sciences Tsinghua University Beijing 100084 China

Although many drugs and therapeutic strategies have been developed for rheumatoid arthritis (RA) treatment, numerous patients with RA fail to respond to currently available agents. In this review, we provide an overview of the complexity of this autoimmune disease by showing the rapidly increasing number of genes associated with RA. We then systematically review various factors that have a predictive value (predictors) for the response to different drugs in RA treatment, especially recent advances. These predictors include but are certainly not limited to genetic variations, clinical factors, and demographic factors. However, no clinical application is currently available. This review also describes the challenges in treating patients with RA and the need for personalized medicine. At the end of this review, we discuss possible strategies to enhance the prediction of drug responsiveness in patients with RA.

关键词： rheumatoid arthritis gene clinical markers therapy

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Machine learning aided design of perovskite oxide materials for photocatalytic water splitting

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Journal of Energy Chemistry 2021年第9期30卷 351-359页

作者： Qiuling Tao Tian lu Ye sheng Long Li Wencong lu Minjie Li Department of Chemistry College of SciencesShanghai UniversityShanghai 200444China Materials Genome Institute Shanghai UniversityShanghai 200444China

Suffering from the inefficient traditional trial-and-error methods and the huge searching space filled by millions of candidates, discovering new perovskite visible photocatalysts with higher hydrogen production rate(RH_(2)) still remains a challenge in the field of photocatalytic water splitting(PWS). Herein, we established structural-property models targeted to RH_(2) and the proper bandgap(Eg) via machine learning(ML) technology to accelerate the discovery of efficient perovskite photocatalysts for PWS. The Pearson correlation coefficients(R) of leave-one-out cross validation(LOOCV) were adopted to compare the performances of different algorithms including gradient boosting regression(GBR), support vector regression(SVR), backpropagation artificial neural network(BPANN), and random forest(RF). It was found that the BPANN model showed the highest R values from LOOCV and testing data of 0.9897 and 0.9740 for RH_(2),while the GBR model had the best values of 0.9290 and 0.9207 for Eg. Furtherly, 14 potential PWS perovskite candidates were screened out from 30,000 ABO3-type perovskite structures under the criteria of structural stability, Eg, conduction band energy, valence band energy and RH_(2). The average RH_(2) of these14 perovskites is 6.4% higher than the highest value in the training data set. Moreover, the online web servers were developed to share our prediction models, which could be accessible in http://***/ocpmdm/material_api/ahfga3d9puqlknig(E_g prediction) and http://***/ocpmdm/material_api/i0 ucuyn3 wsd14940(RH_(2) prediction).

关键词： Perovskite Machine learning Online web service Photocatalytic water splitting Bandgap Hydrogen production rate

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Flag-transitive point-primitive 2-(v,k,4) symmetric designs and two dimensional classical groups

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Applied Mathematics(A Journal of Chinese Universities) 2011年第3期26卷 334-341页

作者： ZHOU sheng-lin TIAN De-lu Department of Mathematics South China University of Technology Guangzhou 510640 China

Let D be a 2-（v, k, 4） symmetric design and G be a flag-transitive point-primitive automorphism group of D with X ≥G ≤Aut（X） where X ≌ PSL2（q）.Then D is a 2-（15,8,4） symmetric design with X = PSL2（9） and ... 详细信息

关键词： Symmetric design flag-transitive point-primitive two dimensional classical group.

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Control of Codimension-2 Bautin Bifurcation in Chaotic Lü System

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Communications in Theoretical Physics 2009年第10期52卷 631-636页

作者： lu Zhuo-sheng DUAN Li-Xia School of Science Beijing University of Posts and Telecommunications Beijing 100876 China School of Science North China University of Technology Beijing 100041 China

In this paper, we design a feedback controller, and analytically determine a control criterion so as to control the codimension-2 Bautin bifurcation in the chaotic Lfi system. According to the control criterion, we determine a potential Bautin bifurcation region （denoted by P） of the controlled system. This region contains the Bautin bifurcation region （denoted by Q） of the uncontrolled system as its proper subregion. The controlled system can exhibit Bautin bifurcation in P or its proper subregion provided the control gains are properly chosen. Particularly, we can control the appearance of Bautin bifurcation at any appointed point in the region P. Due to the relationship between Bantin bifurcation and Hopf bifurcation, the control scheme thereby is also viable for controlling the creation and stability of the Hopf bifurcation. In the controller, there are two terms： a linear term and a nonlinear cubic term. We show that the former determines the location of the Hopf bifurcation while the latter regulates its criticality. We also carry out numerical studies, and the simulation results confirm our analyticai predictions.

关键词： lu system bifurcation control Bautin bifurcation Hopf bifurcation

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An Error Equivalent Model of Revolute Joints with Clearances for Antenna Pointing Mechanisms

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Chinese Journal of Mechanical Engineering 2018年第2期31卷 97-105页

作者： Quan Liu sheng-Nan lu Xi-lun Ding School of Mechanical Engineering and Automation Beihang University

Joint clearances in antenna pointing mechanisms lead to uncertainty in function deviation. Current studies mainly focus on radial clearance of revolute joints, while axial clearance has rarely been taken into consideration. In fact, own?ing to errors from machining and assembly, thermal deformation and so forth, practically, axial clearance is inevitable in the joint. In this study, an error equivalent model(EEM) of revolute joints is proposed with considering both radial and axial clearances. Compared to the planar model of revolute joints only considering radial clearance, the journal motion inside the bearing is more abundant and matches the reality better in the EEM. The model is also extended for analyzing the error distribution of a spatial dual?axis("X–Y" type) antenna pointing mechanism of Spot?beam antennas which especially demand a high pointing accuracy. Three case studies are performed which illustrates the internal relation between radial clearance and axial clearance. It is found that when the axial clearance is big enough, the physical journal can freely realize both translational motion and rotational motion. While if the axial clearance is limited, the motion of the physical journal will be restricted. Analysis results indicate that the consideration of both radial and axial clearances in the revolute joint describes the journal motion inside the bearing more precise. To further validate the proposed model, a model of the EEM is designed and fabricated. Some suggestions on the design of revolute joints are also provided.

关键词： Error modeling Joint clearances Antenna pointing mechanism Radial clearance Axial clearance

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Note on Integer 4-flows in Graphs

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Acta Mathematica Sinica,English Series 2022年第9期38卷 1653-1664页

作者： Xiao WANG You lu sheng Gui ZHANG School of Mathematics and Statistics Northwestern Polytechnical UniversityXi'an 710072P.R.China College of Mathematics and Computer Application Shangluo UniversityShangluo 726000P.R.China

Let G be a bridgeless graph and C be a circuit in *** find a shorter circuit cover of G,Fan proposed a conjecture that if G/C admits a nowhere-zero 4-flow,then G admits a 4-flow(D,f)such that E(G)E(C)?supp(f)and|supp(f)∩E(C)|>3/4|E(C)|,and showed that the conjecture holds if|E(C)|≤19[Combinatorica,37,1097–1112(2017)].In this paper,we prove that the conjecture holds if|E(C)|≤27.

关键词： Integer 4-flow modulo 4-flow circuit

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Effect of Prior Cold Deformation on the Stability of Retained Austenite in GCr15 Bearing Steel

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Acta Metallurgica Sinica(English Letters) 2019年第1期32卷 107-115页

作者： Feng Wang Dong-sheng Qian Xiao-Hui lu School of Materials Science and Engineering Wuhan University of Technology Hubei Key Laboratory of Advanced Technology for Automotive Components School of Automotive Engineering Wuhan University of Technology

In this work, the effect of prior cold deformation on the stability of retained austenite in GCr15 bearing steel was investigated after quenching and tempering treatment. The thermal stability was evaluated by calculating thermal activation energy for decomposition of retained austenite using differential scanning calorimeter. The mechanical stability was investigated according to the strain-induced martensitic transformation behavior of retained austenite under the standard compression testing. It is found that the prior cold deformation not only accelerates the carbide dissolution during the austenitization process but also contributes to the carbon partitioning in the tempering stage due to the higher density of phase boundaries, which results in the improvement of the thermal stability of retained austenite. Due to the enhanced carbide dissolution, the higher carbon content in the prior austenite will intensify the isotropic strain of martensitic transformation. As a consequence, the film-like retained austenite is likely to form under a higher hydrostatic pressure and thus shows a higher mechanical stability. Additionally, it is noteworthy that the benefits of the prior cold deformation to the stability of retained austenite would be saturated when the cold deformation degree is larger than 40%.

关键词： GCr15 bearing steel Prior cold deformation Retained austenite stability

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Parameterized time-frequency analysis to separate multi-radar signals

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Journal of Systems Engineering and Electronics 2017年第3期28卷 493-502页

作者： Wenlong lu Junwei Xie Heming Wang Chuan sheng Air and Missile Defense College Air Force Engineering UniversityXi’an 710051China

Multi-radar signal separation is a critical process in modern reconnaissance systems. However, the complicated battlefield is typically confronted with increasing electronic equipment and complex radar waveforms. The intercepted signal is difficult to separate with conventional parameters because of severe overlapping in both time and frequency domains. On the contrary, time-frequency analysis maps the 1D signal into a 2D time-frequency plane, which provides a better insight into the signal than traditional methods. Particularly, the parameterized time-frequency analysis (PTFA) shows great potential in processing such non stationary signals. Five procedures for the PTFA are proposed to separate the overlapped multi-radar signal, including initiation, instantaneous frequency estimation with PTFA, signal demodulation, signal separation with adaptive filter and signal recovery. The proposed method is verified with both simulated and real signals, which shows good performance in the application on multi-radar signal separation.

关键词： intercepted multi-radar signal parameterized time-frequency analysis demodulation adaptive filtering

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Phase-only pattern synthesis based on gradient-descent optimization

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Journal of Systems Engineering and Electronics 2016年第2期27卷 297-307页

作者： Chengjun lu Weixing sheng Yubing Han Xiaofeng Ma School of Electronic and Optical Engineering Nanjing University of Science and Technology

By applying phase-only technique in array antenna pattern synthesis, antenna arrays can form desired patterns with the use of phase shifters only. A novel phase-only pattern synthesis algorithm is proposed for the passive phased array seeker. This algorithm synthesizes the main beam of the antenna pattern through least-squares approximation, thus minimizing the errors between the actual and the desired main beams. The synthesis problem can be solved by applying gradient-descent optimization. The item for suppressing side lobes is added to the above synthesis problem. To obtain a side lobe level as low as possible, the algorithm assigns different weights to different directions in the side lobe region. The algorithm is run repeatedly and the weights are adjusted adaptively according to the normalized power in the side lobe directions. Detailed examples are presented to demonstrate the accuracy and effectiveness of the proposed approach.

关键词： pattern synthesis phase-only gradient-descent adaptively

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