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Full-scale testing and modeling of the mechanical behavior of shield TBM tunnel joints
Wen-qi Ding,Yi-cheng Peng,Zhi-guo Yan,Bi-wei Shen,He-hua Zhu,Xin-xin Wei 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.45 No.3
For shield TBM (Tunnel Boring Machine) tunnel lining, the segment joint is the most critical component for determining the mechanical response of the complete lining ring. To investigate the mechanical behavior of the segment joint in a water conveyance tunnel, which is different from the vehicle tunnel because of the external loads and the high internal water pressure during the tunnel’s service life, full-scale joint tests were conducted. The main advantage of the joint tests over previous ones was the definiteness of the loads applied to the joints using a unique testing facility and the acquisition of the mechanical behavior of actual joints. Furthermore, based on the test results and the theoretical analysis, a mechanical model of segment joints has been proposed, which consists of all important influencing factors,including the elastic-plastic behavior of concrete, the pre-tightening force of the bolts and the deformations of all joint components, i.e., concrete blocks, bolts and cast iron panels. Finally, the proposed mechanical model of segment joints has been verified by the aforementioned full-scale joint tests.
Xin Wen,Yanlin Jing,Zhiping Hu,Jigang Shao,Jieru Li,Rui Wang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.12
It is of great importance to study the behavior of loess moisture infiltration based on the loess permeability velocity to prevent geological disasters by loess collapsibility and get effective solutions for the problems of practical engineering. In this study, a custom-made permeation device was used to measure the permeation velocity of collapsible loess before and after water immersion and consolidation. The infiltration characteristics of the undisturbed collapsible loess under different consolidation pressures were discussed, and the influence of the pore characteristics on the permeability velocity was analyzed by the mercury injection test. Meanwhile, the correlations of various types of pores on the permeability velocity were studied by the gray relational entropy method to further reveal the water infiltration mechanism in loess. The results showed that the soil is compressed after consolidation and immersion tests, and the pore volume and pore diameter decreases. However, permeability velocity increases rather than decreases, and the self-weight collapsible state has the most significant permeability velocity. To the collapsible loess, the permeability velocity decreases with the increase of soil pore area. Additionally, small pores show the strongest correlation with permeability velocity. The conclusions of this study have a positive role in guiding foundation treatments and slope stability in collapsible loess areas.
Wen, Xin,Chen, Xuecheng,Tian, Nana,Gong, Jiang,Liu, Jie,Rü,mmeli, Mark H.,Chu, Paul K.,Mijiwska, Ewa,Tang, Tao American Chemical Society 2014 Environmental science & technology Vol.48 No.7
<P>The catalytic carbonization of polyolefin materials to synthesize carbon nanotubes (CNTs) is a promising strategy for the processing and recycling of plastic wastes, but this approach is generally limited due to the selectivity of catalysts and the difficulties in separating the polyolefin mixture. In this study, the influence of nanosized carbon black (CB) and Ni<SUB>2</SUB>O<SUB>3</SUB> as a novel combined catalyst system on catalyzing carbonization of polypropylene (PP), polyethylene (PE), polystyrene (PS) and their blends was investigated. We showed that this combination was efficient to promote the carbonization of these polymers to produce CNTs with high yields and of good quality. Catalytic pyrolysis and model carbonization experiments indicated that the carbonization mechanism was attributed to the synergistic effect of the combined catalysts rendered by CB and Ni<SUB>2</SUB>O<SUB>3</SUB>: CB catalyzed the degradation of PP, PE, and PS to selectively produce more aromatic compounds, which were subsequently dehydrogenated and reassembled into CNTs via the catalytic action of CB together with Ni particles. Moreover, the performance of the synthesized CNTs as the electrode of supercapacitor was investigated. The supercapacitor displayed a high specific capacitance as compared to supercapacitors using commercial CNTs and CB. This difference was attributed to the relatively larger specific surface areas of our synthetic CNTs and their more oxygen-containing groups.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2014/esthag.2014.48.issue-7/es404646e/production/images/medium/es-2013-04646e_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es404646e'>ACS Electronic Supporting Info</A></P>
The LQR Baseline with Adaptive Augmentation Rejection of Unmatched Input Disturbance
Xin Wang,Xin Chen,Liyan Wen 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.3
In this paper, disturbance rejection algorithm based on model reference adaptive control (MRAC) augmentationof linear quadratic regulator (LQR) controller is investigated for uncertain turbulence disturbances. Thedirect adaptive state feedback optimal controller based on an LDU gain decomposition parameterization is designedto solve the turbulence compensation problem to enhance control performance. Under the proposed control techniques,the bounded stability is achieved and the controller is able to remain within tight bounds on the matchedand unmatched uncertainties. Finally, simulation results are presented to illustrate the effectiveness of the proposedMRAC augmentation of LQR controller.
Rejection and Attenuation of Multiple Disturbances for a Class of Uncertain Systems
Xin-Yu Wen,Ruo-Fan Li,Songyin Cao 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.7
A novel anti-disturbance strategy for a class of uncertain systems is investigated. Besides the unknown frequency sinusoidal, the controlled plant is subjected to bounded noise and unknown nonlinear term simultaneously. Through the construction of auxiliary observer, the sinusoidal is represented in a parametric uncertainty form. Only one unknown scalar needs estimating to construct compensation signal, meanwhile the unwanted nonlinear operation between frequency and equivalent disturbance can be removed. By integrating a feedback control law, all the unexpected dynamics can be rejected and attenuated respectively, where the conditions on the stability and optimal performance are also provided. Finally, a computer simulation example is presented to illustrate the effectiveness and the applicability of the suggested method.
Head-on Collision Between Two Envelope Solitary Waves in a Granular Medium
Wen-Qing Du,Jian-An Sun,Juan-Fang Han,Wen-Shan Duan,Yang-Yang Yang,Xin Jiang 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.11
We investigated the head-on collision between two envelope solitary waves. Head-on collisions between two envelope solitary waves are first discussed in one-dimension (1D) granular chains. The interesting result is that no phase shift or phase delay detected after the head-on collision between two envelope solitary waves. The maximum amplitude during the head-on collision between two envelope solitary waves is also found to be less than the sum of the amplitudes of the two envelope solitary waves, but is larger than the amplitude of the either of the envelope solitary waves.