检索结果-内蒙古大学图书馆

Experimental Study on Geogrid-Soil Interface Properties Based on Pullout Tests: A case Study

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Wang, Zhijie Zhang, Guowei Yang, Guangqing Qin, Yan Zhou, Shiguang State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China China Railway Society Beijing100844 China

The geogrid-soil interaction, which is crucial to the safety and stability of reinforced soil structures, is affected by the parameters of soils and geogrids. To investigate the influence of backfill and geogrid on their interface behavior of the reinforced soil retaining walls in Yichang section of Shanghai-chongqing-Sichuan high-speed railway, a series of geogrid pullout tests were carried out. The development and evolution law of pullout force-pullout displacement curves and interface characteristics between geogrid and soil under various testing conditions were analyzed. The results showed that with increasing water content, the geogrid pullout force decreased under the same pullout displacement. The apparent friction angle of the geogrid-soil interface showed a slowly increasing trend with increasing water content. The variation of the apparent friction angle ranged between 9.2° and 10.7°. The apparent cohesion, however, decreased rapidly with increasing water content. With increasing degree of compaction, the apparent friction angle and the apparent cohesion of the geogrid-soil interface gradually increased. The change of the apparent cohesion with the compaction degree was more significant. When the degree of compaction increased from 0.87 to 0.93, the apparent cohesion increased around 7 times. The tensile strength of geogrid has certain influence on its pullout force-pullout displacement relationship. High-strength geogrid could significantly improve the mechanical properties of the geogrid-soil interface. The investigation results can provide some reference for the design and construction of geogrid reinforced soil structures. © 2024, The Authors. All rights reserved.

关键词： Tensile strength

Problems and corrections of classical Mathematical Model for Piecewise Linear system

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Shen, Yongjun Zhang, Ruiliang Han, Dong Liu, Xiaoyan School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Department of Electrical and Information Engineering Hebei Jiaotong Vocational and Technical College Shijiazhuang050035 China

Due to the existence of gap or backlash, many mechanical systems can be simplified into piecewise linear models. The dynamic study on mechanical system should be based on reliable mathematical model, so that it is very important to determine the contact point and separation point between the primary system and the auxiliary spring system (ASS) in the piecewise linear systems. In most existing literatures on piecewise linear systems, the contact point and the separation point of the mathematical model are fixed at the gap. But in this paper, it is found that the contact point and separation point actually change with the system parameters when the ASS contains damper, which implies the most existing mathematical model are incorrect. It is firstly demonstrated through numerical solution that the primary system will prematurely separate from the ASS before reaching the gap under harmonic excitation, which shows the incorrectness of the classical mathematical model. Then, based on the mechanical model and engineering practice, two corrected mathematical models are proposed. And the motions of the primary system and ASS after prematurely separation in the corrected models are studied. Finally, through comparison of the contact point, separation point, amplitude-frequency curves and motion state between the corrected models and the classical mathematical model, it can be concluded that the corrected models are more reasonable. And the comparisons with the experimental data implies that the corrected models can better reflect the engineering practice. These results will be helpful to the study and design of the piecewise linear system. © 2024, The Authors. All rights reserved.

关键词： Piecewise linear techniques

Effect of Deformation Twinning on Microstructure Refinement of Fe-38mn Alloy During Friction Stir Processing

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Sang, Deli Xin, Xiaoli Fu, Ruidong Li, Yijun College of Materials Science and Engineering Shijiazhuang Tiedao University Hebei Shijiazhuang050000 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Hebei Shijiazhuang050043 China State Key Laboratory of Metastable Materials Science and Technology Yanshan University Hebei Qinhuangdao066004 China

The effect of deformation twinning on microstructure refinement was investigated for Fe-38Mn alloy during friction stir processing. It was proved that the friction stir processing microstructure of Fe-38Mn alloy was gradient distribution. The stir zone contained both recrystallized grains and fine deformed grains with average grain size of about 15 μm, and the proportion of twin boundaries in the deformed grain zone was up to 35%. Moreover, the cyclic multidirectional shear induced micro-shear bands and sub-grains with high density dislocations, as well as plentiful deformation twins. The microstructure refinement of Fe-38Mn alloy during friction stir processing resulted from the dynamic recrystallization mechanism and twinning mechanism. In addition, the cyclic multidirectional shear deformation enhanced the deformation twinning effect, so that the microstructure refinement process was completed quickly and effectively. The above works indicate a dynamic mechanism of microstructure refinement in term of the deformation twinning during friction stir processing. © 2022, The Authors. All rights reserved.

关键词： Binary alloys

Research on Intelligent Trajectory Finding and Escape Dilemma Tracking Strategy of Tire Blowout Vehicle

学校读者我要写书评

暂无评论

SSRN 2023年

作者： Han, Zexuan Lu, Yongjie Li, Haoyu Zhang, Junning School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhaung Tiedao University Shijiazhuang China Department of Engineering Mechanics Shijiazhuang Tiedao University Shijiazhuang China School of Mechanicsand Engineering Science Shanghai University Shanghai China

To improve the safety and stability after a vehicle tire blowout in complex road environment, an intelligent trajectory finding and escape dilemma tracking strategy integrating decision-making, planning and control is proposed. The nonlinear static Dugoff tire formula is improved based on the dynamic change of tire blowout mechanical parameters. combined with multi-body vehicle dynamics model and steering control driver model, a joint simulation platform for tire blowout vehicle is established. considering the real-time state of the vehicle and the complexity of the road environment, the original driving trajectory is kept. And based on the Bessel curve method and the fifth-order polynomial method, the vehicle obstacle avoidance and lane change path are planned. The model predictive control algorithm is designed to achieve escape dilemma tracking control of the vehicle after tire blowout. The carSim/Simulink joint simulation test is used to verify the control effect of the intelligent trajectory finding and escape dilemma tracking strategy in different scenarios. The results show that this strategy can reasonably and effectively plan the trajectory of keeping, obstacle avoidance and lane change, and bring vehicle out of danger in time while maintaining safety and stability. © 2023, The Authors. All rights reserved.

关键词： Trajectories

Fault Diagnosis Method for Multiple Sources based on IESFSc-SSRgram

学校读者我要写书评

暂无评论

Fault Diagnosis Method for Multiple Sources based on IESFSC-...

International conference on Sensing, Diagnostics, Prognostics, and control (SDPc)

作者： Wu Zhihao Gong Shixian Huang chenguang Jin Hang Liu Zechao National Engineering Laboratory CRRC Qingdao Sifang Locomotive and Rolling Stock Co. Ltd Qingdao China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structure and School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang China Weichai Power Co. Ltd. Data Management Engineering Center Weifang China Institute of Magnetic Levitation and Electromagnetic Propulsion China Aerospace Science and Industry Corporation Limited Beijing China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

ISBN: (数字)9798350388855

ISBN: (纸本)9798350388862

The division and determination of frequency bands are always core problems in fault diagnosis methods for rotating machinery. currently, the frequency band division strategy of most fault diagnosis methods is the 1/3-binary tree or realized by wavelet packet transform (such as fast kurtosis diagram and Autogram). This method is relatively fixed, making it difficult to accurately cover the resonance frequency band and achieve multi-source fault identification. To address the above problems, an adaptive frequency band division strategy based on Fast Spectral correlation (FSc) and Scale-Space Representation (SSR) is proposed. The enhanced enveloping spectrum (EES) of each frequency band after division is obtained, and the improved Fault Quantification Index (IFQI) is used to measure the richness of target information in each enveloped spectrum (ES), generating a two-dimensional diagram. The envelope spectrum with the largest IFQI value is selected as the improved envelope spectrum (IES) obtained by the FSc and SSR division strategy (IESFSc-SSRgram), enabling the fault diagnosis of the axle box bearing. The effectiveness and superiority of the proposed method in identifying multi-source concurrent faults in the wheelset bearing system are verified by comparing it with the traditional method.

关键词： Fault diagnosis correlation Resonant frequency Frequency conversion Wavelet packets Power capacitors Frequency measurement Sensors Indexes Frequency control

Illumination robust loop closure detection with the constraint of pose

学校读者我要写书评

暂无评论

arXiv

arXiv 2019年

作者： Deli, Yan Wenkun, Tuo Weiming, Wang Shaohua, Li State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Electrical and Electronic Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China School of Electronic and Information Engineering Beijing Jiaotong University Beijing100044 China

Background: Loop closure detection is a crucial part in robot navigation and simultaneous location and mapping (SLAM). Appearance-based loop closure detection still faces many challenges, such as illumination changes, perceptual aliasing and increasing computational complexity. Method: In this paper, we proposed a visual loop-closure detection algorithm which combines illumination robust descriptor DIRD and odometry information. The estimated pose and variance are calculated by the visual inertial odometry (VIO), then the loop closure candidate areas are found based on the distance between images. We use a new distance combing the the Euclidean distance and the Mahalanobis distance and a dynamic threshold to select the loop closure candidate areas. Finally, in loop-closure candidate areas, we do image retrieval with DIRD which is an illumination robust descriptor. Results: The proposed algorithm is evaluated on KITTI_00 and EuRoc datasets. The results show that the loop closure areas could be correctly detected and the time consumption is effectively reduced. We compare it with SeqSLAM algorithm, the proposed algorithm gets better performance on PR-curve. copyright © 2019, The Authors. All rights reserved.

关键词： Mapping

Response characteristics of a Piezoelectric Semiconductor Layer Under a Rigid Spherical Indenter

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Liu, Jinxi Gao, Shijing Ju, chengjian Nie, Guoquan chen, Weiqiu State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China Department of Engineering Mechanics Hebei Key Laboratory for Mechanics of Intelligent Materials and Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Key Lab of CAD & CG Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Department of Engineering Mechanics Zhejiang University Hangzhou310027 China

This paper considers the axisymmetric frictionless indentation responses of a piezoelectric semiconductor (PSc) layer, which is perfectly bonded to a rigid substrate and acted on by a rigid spherical indenter. While both the indenter and the rigid substrate are assumed to be electrically insulating, the interaction of piezoelectricity and semiconducting property of PSc is fully taken into consideration. By the Hankel integral transformation, the indentation problem is reduced to a Fredholm integral equation of the second kind, which is solved numerically. The variations of the indentation force, electric potential and contact radius with the indentation depth are obtained. The effects of the layer thickness, indenter size and semiconducting on the variation relationships are analyzed in detail to achieve a better understanding of the response of the PSc layer under indentation. Furthermore, the theoretical results based on the singular integral equation method are verified by the finite element simulation. © 2024, The Authors. All rights reserved.

关键词： Piezoelectricity

Investigation on the reinforcement effect of a bedding slope affected by a landsliding block

学校读者我要写书评

暂无评论

Arabian Journal of Geosciences 2022年第6期15卷 1-20页

作者： Zhang, Fei Yang, Tianhong Li, Lianchong Zhu, Xinping Key Laboratory of Roads and Railway Engineering Safety Control Shijiazhuang Tiedao University Ministry of Education Shijiazhuang China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang China Center of Rock Instability and Seismicity Research School of Resources and Civil Engineering Northeastern University Shenyang Liaoning China China Coal Technology and Engineering Group Shenyang Research Institute Fushun China

The south slope of Fushun west open-pit mine located in Northeast china is a high-deep rock slope. In the last few years, a landsliding block has gradually formed in the south slope. Owing to the effect of sliding force caused by the sliding block, some damage has occurred on the foundation of Kengkou refinery which constructed in the west of the south slope. To improve the stability of the refinery foundation, three group micro-pile structures were employed to cut off the drag of the sliding block and reinforce the refinery on the southwest slope. In this study, a comprehensive method combining the microseismic monitoring technique and numerical simulation method was used, the stability of the southwest slope was evaluated, and reinforcement mechanism was deeply analyzed. A microseismic monitoring system is established on-site to obtain useful information about the damage energy, location, and magnitude of the rocks in the southwest slope. Thus, the west boundary of the landslide in the south slope of the open-pit is determined. By analyzing the numerical results, the stress concentration is discovered mainly around the micro-pile structures and near the west boundary. After reinforcement, the displacement decrease in the south-north direction is apparent. To investigate the interaction mechanism between the micro-pile and the surrounding rock mass, a local 3D numerical model is employed to help understand auxiliary information about the stress state and stress redistribution induced by failure in the surrounding rock mass. It is shown that the reinforcement effect becomes more and more evident with the increase in the number of employed micro-piles. The numerical results and in situ GPS displacement monitoring data illustrate that the micro-pile structures have an excellent strengthening result in controlling the deformation of the slope. The comprehensive methodology provides an effective way to estimate the stability and the reinforcement effect of the slope und

关键词：

Invariant cubature kalman filter for monocular visual inertial odometry with line features

学校读者我要写书评

暂无评论

arXiv

arXiv 2019年

作者： Deli, Y.A.N. chunhui, W.U. Wang, Weiming Song, Yu Li, Shaohua State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Electrical and Electronic Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China School of Electronic and Information Engineering Beijing Jiaotong University Beijing100044 China

To achieve robust and accurate state estimation for robot navigation, we propose a novel Visual Inertial Odometry(VIO) algorithm with line features upon the theory of invariant Kalman filtering and cubature Kalman Filter (cKF). In contrast with conventional cKF, the state of the filter is constructed by a high dimensional Matrix Lie group and the uncertainty is represented using Lie algebra. To improve the robustness of system in challenging scenes, e.g. low-texture or illumination changing environments, line features are brought into the state variable. In the proposed algorithm, exponential mapping of Lie algebra is used to construct the cubature points and the re-projection errors of lines are built as observation function for updating the state. This method accurately describes the system uncertainty in rotation and reduces the linearization error of system, which extends traditional cKF from Euclidean space to manifold. It not only inherits the advantages of invariant filtering in consistency, but also avoids the complex Jacobian calculation of high-dimensional matrix. To demonstrate the effectiveness of the proposed algorithm, we compare it with the state-of-the-art filtering-based VIO algorithms on Euroc datasets. And the results show that the proposed algorithm is effective in improving accuracy and robustness of estimation. copyright © 2019, The Authors. All rights reserved.

关键词： Kalman filters