Failure behaviors of C/C composite tube under lateral compression loading

Yantao Gao,Yuexia Guan,Ke Li,Min Liu,Can Zhang,Jinliang Song 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.7

Mechanical responses and failure behaviors of advanced C/C composite tube are very important for structural component design in nuclear reactor. In this study, an experimental investigation was conducted to study mechanical properties of C/C composite tube. Quasi-static compression loading was applied to a type of advanced composite tube to determine the response of the quasi-static load displacement curve during progressive damage. Acoustic emissions (AE) signals were captured and analyzed to characterize the crack formation and crack development. In addition, the crack propagation of the specimens was monitored by imaging technique and failure mode of the specimen was analyzed. FEM is appled to simulate the stress distribution. Results show that advanced C/C composite tube exhibits considerable energy absorption capability and stability in load-carrying capacity.

Seismic Responses of a Tunnel-Soil-Surface Structure System under Multidimensional Near-Field and Far-Field Seismic Waves through a Shaking Table Test

Yantao Li,Ye Tian,Jinhui Zong 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.11

In this paper, a tunnel-soil-surface structure system is taken as the research object, and shaking table tests of multidimensional near-field and far-field seismic waves are carried out to study the dynamic response law of the tunnel, the soil and the surface structure. The test results show that the response of the soil under the far-field seismic wave is relatively stronger, but due to the high-energy velocity pulse of the near-field seismic wave, the difference in accelerationresponse of the soil under near-field and far-field seismic waves gradually decreases as the input ground motion intensity increases. The existence of the tunnel causes the seismic response of the soil near the tunnel to be obviously different from that of the soil far away from the tunnel. After considering the vertical earthquake action, the acceleration response of the soil slightly increases. The surface structure-pile foundation has a certain influence on the seismic response of the middle section of the shallow tunnel. In addition, the input of vertical ground motion causes greater tensile strain in the tunnel. For the deformation of the surface structure, the period of acceleration response spectra of vertical ground motion close to the fundamental period of the structure in the vertical direction leads to a significant change in the vertical response, which is also the reason for the increase of the lateral deformation. The vertical seismic component has a significant influence on the dynamic response of the tunnel-soil-surface structure system, and the influence of vertical ground motion should be fully considered in seismic design.

A Highly Secure Identity-Based Authenticated Key-Exchange Protocol for Satellite Communication

Yantao, Zhong,Jianfeng, Ma The Korea Institute of Information and Commucation 2010 Journal of communications and networks Vol.12 No.6

In recent years, significant improvements have been made to the techniques used for analyzing satellite communication and attacking satellite systems. In 2003, a research team at Los Alamos National Laboratory, USA, demonstrated the ease with which civilian global positioning system (GPS) spoofing attacks can be implemented. They fed fake signals to the GPS receiver so that it operates as though it were located at a position different from its actual location. Moreover, Galileo in-orbit validation element A and Compass-M1 civilian codes in all available frequency bands were decoded in 2007 and 2009. These events indicate that cryptography should be used in addition to the coding technique for secure and authenticated satellite communication. In this study, we address this issue by using an authenticated key-exchange protocol to build a secure and authenticated communication channel for satellite communication. Our protocol uses identity-based cryptography. We also prove the security of our protocol in the extended Canetti-Krawczyk model, which is the strongest security model for authenticated key-exchange protocols, under the random oracle assumption and computational Diffie-Hellman assumption. In addition, our protocol helps achieve high efficiency in both communication and computation and thus improve security in satellite communication.

Characterization of a 3D Auxetic Warp-knitted Spacer Fabric by Synchrotron Radiation X-ray Computed Tomography

Yantao Gao,Pibo Ma,Ke Li,Jin Xu 한국섬유공학회 2020 Fibers and polymers Vol.21 No.4

Auxetic fabrics have many potential applications in technical textiles. Auxetic 3D warp-knitted spacer fabric canbe produced by adoption of some special geometrical configuration. Characterization of the geometrical configurations is ofvital significance to understand their auxetic property. In this paper, a typical 3D auxetic warp-knitted spacer fabric wasstudied by synchrotron radiation x-ray computed tomography (SR-CT). Fiber distribution in the fabric was clearly obtainedand different types of yarn were extracted separatively. 3D image reconstructed by synchrotron radiation X-ray computedtomography was consistent with the designed geometrical configuration. Besides, 3D model reconstructed lays thefoundation for further numerical analysis by FEA.

Aerosol Synthesis of Cargo-FilledGraphene Nanosacks

Chen, Yantao,Guo, Fei,Jachak, Ashish,Kim, Sang-Pil,Datta, Dibakar,Liu, Jingyu,Kulaots, Indrek,Vaslet, Charles,Jang, Hee Dong,Huang, Jiaxing,Kane, Agnes,Shenoy, Vivek B.,Hurt, Robert H. American ChemicalSociety 2012 Nano letters Vol.12 No.4

<P>Water microdroplets containing graphene oxide and a secondsoluteare shown to spontaneously segregate into sack-cargo nanostructuresupon drying. Analytical modeling and molecular dynamics suggest thesacks form when slow-diffusing graphene oxide preferentially accumulatesand adsorbs at the receding air–water interface, followed bycapillary collapse. Cargo-filled graphene nanosacks can be nanomanufacturedby a simple, continuous, scalable process and are promising for manyapplications where nanoscale materials should be isolated from theenvironment or biological tissue.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2012/nalefd.2012.12.issue-4/nl2045952/production/images/medium/nl-2011-045952_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl2045952'>ACS Electronic Supporting Info</A></P>

A Highly Secure Identity-Based Authenticated Key-Exchange Protocol for Satellite Communication

Zhong Yantao,Ma Jianfeng 한국통신학회 2010 Journal of communications and networks Vol.12 No.6

In recent years, significant improvements have beenmade to the techniques used for analyzing satellite communication and attacking satellite systems. In 2003, a research team at Los Alamos National Laboratory, USA, demonstrated the ease with which civilian global positioning system (GPS) spoofing attacks can be implemented. They fed fake signals to the GPS receiver so that it operates as though it were located at a position different from its actual location. Moreover, Galileo in-orbit validation element A and Compass-M1 civilian codes in all available frequency bands were decoded in 2007 and 2009. These events indicate that cryptography should be used in addition to the coding technique for secure and authenticated satellite communication. In this study, we address this issue by using an authenticated key-exchange protocol to build a secure and authenticated communication channel for satellite communication. Our protocol uses identity-based cryptography. We also prove the security of our protocol in the extended Canetti-Krawczyk model, which is the strongest security model for authenticated key-exchange protocols, under the randomoracle assumption and computational Diffie-Hellman assumption. In addition,our protocol helps achieve high efficiency in both communication and computation and thus improve security in satellite communication.

Progressive multi-atlas label fusion by dictionary evolution

Song, Yantao,Wu, Guorong,Bahrami, Khosro,Sun, Quansen,Shen, Dinggang Elsevier 2017 Medical image analysis Vol.36 No.-

<P><B>Abstract</B></P> <P>Accurate segmentation of anatomical structures in medical images is important in recent imaging based studies. In the past years, multi-atlas patch-based label fusion methods have achieved a great success in medical image segmentation. In these methods, the appearance of each input image patch is first represented by an <I>atlas patch dictionary</I> (in the image domain), and then the latent label of the input image patch is predicted by applying the estimated representation coefficients to the corresponding anatomical labels of the atlas patches in the <I>atlas label dictionary</I> (in the label domain). However, due to the generally large gap between the patch appearance in the <I>image domain</I> and the patch structure in the <I>label domain</I>, the estimated (patch) representation coefficients from the image domain may not be optimal for the final label fusion, thus reducing the labeling accuracy. To address this issue, we propose a novel label fusion framework to seek for the suitable label fusion weights by progressively constructing a dynamic dictionary in a layer-by-layer manner, where the intermediate dictionaries act as a sequence of guidance to steer the transition of (patch) representation coefficients from the image domain to the label domain. Our proposed multi-layer label fusion framework is flexible enough to be applied to the existing labeling methods for improving their label fusion performance, i.e., by extending their single-layer <I>static</I> dictionary to the multi-layer <I>dynamic</I> dictionary. The experimental results show that our proposed progressive label fusion method achieves more accurate hippocampal segmentation results for the ADNI dataset, compared to the counterpart methods using only the single-layer <I>static</I> dictionary.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A progressive multi-atlas label fusion method by deep dictionary evolution is proposed. </LI> <LI> A sequence of intermediate dictionaries was constructed to progressively optimize the weights for label fusion. </LI> <LI> As an extension of the conventional single-layer methods by improving their label fusion performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Investigation on failure assessment method for nuclear graphite components

Gao, Yantao,Tsang, Derek K.L. Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.1

Super fine-grained graphite is a type of advanced nuclear graphite which was developed for Molten Salt Reactor (MSR). It is necessary to establish a failure assessment method used for nuclear graphite components in MSR. A modified assessment approach based on ASME BPVC-III-5_2017 is presented. The new approach takes a new parameter, KIC, into account and abandons the parameter, grain size, which is unrealistic for super fine-grained graphite as the computation is enormous if we use conventional methods. Three methodologies (KTA 3232, ASME, New approach) were also evaluated by theoretical prediction and experimental verification. The results indicated the new developed code can be used for design and failure assessment of super fine-graphite components and has more extensive applicability.

Research progress on the interfacial phases of ceramic matrix composites

Weina Guo,Yantao Gao 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.2

Continuous fiber toughened ceramic matrix composites (CMCs) have a wide range of applications in fields of aerospacevehicles and nuclear power plants because of their excellent properties. As one of the basic components of CMCs, theinterfacial phase plays a great role in the performance of CMCs. By adjusting the interfacial phase, the tougheningmechanisms such as fiber pull-out and debonding of CMCs can be brought into full play. The paper introduced the designprinciples of interfacial engineering of CMCs. The methods of interfacial preparation and interfacial strength testing of CMCswere summarized, and then the advantages and disadvantages of each methods were analyzes. The recent status of interfacephase of CMCs was also reviewed. Finally, the development direction of interface phase of CMCs was prospected.

Multiple-mode Adaptive State Estimator for Nonlinear Switched Systems

Junqi Yang,Yantao Chen,Lizhi Cui 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.4

This paper deals with the issue of state estimator design for nonlinear switched systems. A multiplemodeadaptive estimator is proposed under mode-dependent average dwell time (MDADT) switching, and theswitching signal with MDADT constraint is also obtained to guarantee the exponential stability of estimation errordynamics, where the Lipschitz constant may be unknown since it is adaptively adjusted by designing an adaptationlaw. Based on both Lyapunov stable theory and the feasible solution of an optimization problem with linear matrixinequality constraint, the gain matrices and switching signals are provided, respectively. The sufficient conditionsof the existence of multiple-mode adaptive switched estimator are also derived. Meanwhile, the above methodsare also extended to the case of the average dwell time (ADT) switching, and an algorithm is given to summarizethe implementation of the proposed estimators. Finally, the effectiveness of the designed methods is illustrated bysimulation examples.