Researching on X-Band Electromagnetic Interference Shielding Efficiency of MWCNTs Buckypapers Inserted with Mn Nanopowder

Shaowei Lu,Yaoyao Bai,Jijie Wang,Chenxu Zhao,Wei Li,Xiaoqiang Wang,Zhenwei Huang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.6

Ultrathin multi-walled carbon nanotubes (MWCNTs) buckypapers inserted with Mn nanopowder were fabricated via vacuum filtration method, at a lower manufacturing cost and easier operation. The buckypapers were characterized structurally using scanning electron microscopy, energy-dispersive spectrometer and X-ray diffraction. Electromagnetic interference (EMI) shielding effectiveness (SE) of MWCNTs buckypapers inserted with Mn nanopowder (0–30 wt.%) were tested in X-band (8.2–12.4 GHz). When the blended Mn nanopowder content is 20 wt.%, the buckypaper exhibits much higher EMI SE of average value up to 42 dB with the thickness of only 0.11 mm. Further, this buckypaper is flexible and lightweight, and can be integrated with resin matrix composites. Thus, the results and techniques promise a simple and effective approach to achieve lightweight and ultrathin composite films for a wide application prospect in the field of EMI shielding and microwave absorption.

Integration of Multipath Transmission into the IMS Framework

( Shaowei Liu ),( Weimin Lei ),( Wei Zhang ),( Hao Li ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.8

IP multimedia subsystem (IMS) is an open standardized architecture for delivering multimedia service over IP network in a route-agnostic manner. With the increasing popularity of conversational class service, the delivery of a traffic flow with a certain bandwidth demand over a single network path is either not possible or not cost-effective. Multipath transmission is considered to be a promising solution to provide high-quality delivery service. This paper proposes a software defined service overlay network (SDSON) based multipath transmission framework for IMS, which is complementary to existing network architecture. The framework transforms original two-party session negotiation into three-party session negotiation that supports participants to negotiate multipath transmission capacity and path information by signaling message. Based on existing IETF standards, SIP and SDP are scalable to support these functions. Finally, the proposed framework is fully implemented on open source platform and examined by experiments. Experimental results show that multipath-enabled IMS is an effective way to improve the delivery performance of conversational class service.

Copy-move Forgery Detection Robust to Various Transformation and Degradation Attacks

( Jiehang Deng ),( Jixiang Yang ),( Shaowei Weng ),( Guosheng Gu ),( Zheng Li ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.9

Trying to deal with the problem of low robustness of Copy-Move Forgery Detection (CMFD) under various transformation and degradation attacks, a novel CMFD method is proposed in this paper. The main advantages of proposed work include: (1) Discrete Analytical Fourier-Mellin Transform (DAFMT) and Locality Sensitive Hashing (LSH) are combined to extract the block features and detect the potential copy-move pairs; (2) The Euclidian distance is incorporated in the pixel variance to filter out the false potential copy-move pairs in the post-verification step. In addition to extracting the effective features of an image block, the DAMFT has the properties of rotation and scale invariance. Unlike the traditional lexicographic sorting method, LSH is robust to the degradations of Gaussian noise and JEPG compression. Because most of the false copy-move pairs locate closely to each other in the spatial domain or are in the homogeneous regions, the Euclidian distance and pixel variance are employed in the post-verification step. After evaluating the proposed method by the precision-recall-F1 model quantitatively based on the Image Manipulation Dataset (IMD) and Copy-Move Hard Dataset (CMHD), our method outperforms Emam et al.’s and Li et al.’s works in the recall and F1 aspects.

Effect of solution properties on the interaction of 90Sr(II) with GMZ bentonite

Xin Chen,Jin Wang,Shaowei Wang,Fengliang Ma,Xiaopeng Chen,Jiaxing Li 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.11

The bentonite from gaomiaozi county (Inner Mongolia, China) (GMZ bentonite) has been selected as the candidate of backfill material in China for nuclear waste repository. Herein, the sorption of 90Sr(II) on GMZ bentonite was investigated as a function of contact time, solid content, pH, ionic strength, foreign ions, humic acid (HA) and temperature. The results indicated that the sorption of 90Sr(II) was mainly dominated by ion exchange or outer-sphere surface complexation at low pH, whereas inner-sphere surface complexation was the main sorption mechanism at high pH values. The thermodynamic parameters (ΔH0, ΔS0 and ΔG0) calculated from the temperature-dependent sorption isotherms indicated that the sorption of 90Sr(II) on GMZ bentonite was an endothermic and spontaneous process. The results provided important information for the interaction mechanism of 90Sr(II) with GMZ bentonite, and is crucial for the evaluation of GMZ bentonite as backfill material.

Distributed and Real-time Integrated Simulation System on Avionics

Yaoming Zhou,Yaolong Liu,Shaowei Li,Yuhong Jia 한국항공우주학회 2017 International Journal of Aeronautical and Space Sc Vol.18 No.3

In order to achieve iterative design in early R&D period, a Distributed and Real-time Integrated Simulation System for avionics based on a Model-Based Systems Engineering (MBSE) method is proposed. The proposed simulation system includes driver, simulation model, monitor, flight visual model and aircraft external model. The effect of this simulation system in iterative design and system verification is testified by several use cases. The result shows that the simulation system, which can play an important role in iterative design and system verification, can reduce project costs and shorten the entire R&D period.

Effects of Grouting Defects in a Duct on the Bonding of Prestressing Strands

Rong Guo,Zhichao Zhen,Shaowei Zhao,Cunan Li 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.4

Insufficient grouting has a great effect on the bonding performance of pressing stand for a post-tensioned prestressed concrete beam, which leads to a decrease of beam’s bending capacity. This study focused on the influence of defects of local grouting length and grouting fullness on the prestressing strand’s bond performance. The prestressing strand pull-out test was used to evaluate the bonding performance of pressing stand with different defects of local grouting length and grouting fullness. The results indicate that two forms of grouting defects reduce the bonding properties of a prestressing strand, when the slip of the free end of prestressing strand is 0.12 mm (s = 0.12 mm), the bond stress decreases briefly. To analyze the bonding mechanism of the prepressing strand in duct, the bond stresses τ0 and τu at s = 0.12 mm and s = 25 mm were adopted as the characteristic parameters of bond stress to deduce the calculation formula of the bond strength by fitting the test data. A bond-slip constitutive model of prestressing strand in duct under two classes defects was proposed by improving the modified Eligehausen, Popov and Bertero (BPE) model of fiber reinforced polymer (FRP) rebars.

An adaptive marine predator algorithm based optimization method for hood lightweight design

Zhang Chenglin,He Zhicheng,Li Qiqi,Chen Yong,Chen Shaowei,NIE XINYU 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.3

The lightweight design of the hood is crucial for the structural optimization of an entire vehicle. However, traditional high-fidelity-based lightweight methods are time-consuming due to the complex structures of the hood, and the lightweight results heavily rely on engineering experiences. To this end, an improved adaptive marine predator algorithm (AMPA) is proposed to solve this problem. Compared to the original marine predator algorithm (MPA), the proposed AMPA adapts to optimization problems through three enhancements, including chaotic theory-based initialization, a mixed search strategy, and dynamic partitioning of iteration phases. Experimental comparisons of AMPA, MPA, and eight state-of-the-art algorithms are conducted on IEEE CEC2017 benchmark functions. AMPA outperforms the others in both 30- and 50-dimensional experiments. Friedman and Wilcoxon’s sign-rank tests further confirm AMPA’s superiority and statistical significance. An implicit parametric model of the hood is generated, and the critical design variables are determined through global sensitivity analysis to realize hood lightweight. The stacking method is employed to construct a surrogate meta-model of the hood to accelerate the optimization efficiency of the vehicle hood. Utilizing the meta-model and the proposed AMPA, the hood mass is reduced by 7.43% while all six static and dynamic stiffness metrics are enhanced. The effectiveness of the proposed optimization method is validated through finite element analysis.

Mapping the Mangrove Forest Restoration Potential and Conservation Gaps in China Based on Random Forest Model

Zhonghua Yu,Wei Li,Shaowei Zhang,Buqing Zhong,Jun Wang,이시영,최재혁,Shulin Deng 인간식물환경학회 2022 인간식물환경학회지 Vol.25 No.4

Background and objective: The area of mangroves is gradually decreasing globally, and mangroves are already one of the most threatened ecosystems. Despite net growth in the mangrove areas in China, the restoration potential of mangroves is still insufficient. This study proposed the Random forest model as an excellent data mining method to map the restoration potential based on the predicted probability of mangrove habitat suitability. Methods: We demonstrated the vital environmental variables influencing habitat suitability. The de-cisive advantages of RFM were parsimonious (variables selection), cost-effective (us-ing existing open-source data), accurate (training AUC was 0.89, testing AUC was 0.91), highly efficient (fast-training speed); and its results had high explanatory power. Here, we first mapped the conservation gaps using the RFM. Results: The results showed that temperature was the most important environmental factor influencing the habitat suit-ability of mangroves. The northern limit of suitable areas was around 24°44' N. The theoretical suitable habitat area for mangrove was 196,566.6 ha (the highly suitable area was 32,551.4 ha, the medium suitable area was 164,015.2 ha). The potential area for mangrove restoration was 176,264 ha (Guangdong with 104215.4 ha, Guangxi with 65957.5 ha). Conclusion: We proposed 24 sites with conservation gaps for mangrove forests restoration and nine potential sites as examples for the further restoration plan. We took one example site with high restoration potential for further explanation: how the key environmental factors influence the habitat suitability and how to use the infor-mation to guide the restoration strategies. RFM can be used as a data mining algo-rithm for the utmost use of the presence-only ecological data, objectively evaluating the suitability of species distribution, and providing scientifically technical data for species restoration planning.

Distributed and Real-time Integrated Simulation System on Avionics

Zhou, Yaoming,Liu, Yaolong,Li, Shaowei,Jia, Yuhong The Korean Society for Aeronautical and Space Scie 2017 International Journal of Aeronautical and Space Sc Vol.18 No.3

In order to achieve iterative design in early R&D period, a Distributed and Real-time Integrated Simulation System for avionics based on a Model-Based Systems Engineering (MBSE) method is proposed. The proposed simulation system includes driver, simulation model, monitor, flight visual model and aircraft external model.The effect of this simulation system in iterative design and system verification is testified by several use cases. The result shows that the simulation system, which can play an important role in iterative design and system verification, can reduce project costs and shorten the entire R&D period.

Study on the influence of flow blockage in severe accident scenario of CAP1400 reactor

Gao Pengcheng,Zhang Bin,Li Jishen,Miao Fan,Tang Shaowei,Cao Sheng,Yang Hao,Shan Jianqiang 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3

Deformed fuel rods can cause a partial blockage of the flow area in a subchannel. Such flow blockage will influence the core coolant flow and further the core heat transfer during the reflooding phase and subsequent severe accidents. Nevertheless, most of the system analysis codes simulate the accident process based on the assumed flow blockage ratio, resulting in inconsistencies between simulated results and actual conditions. This paper aims to study the influence of flow blockage in severe accident scenario of the CAP1400 reactor. First, the flow blockage model of ISAA code is improved based on the FRTMB module. Then, the ISAA-FRTMB coupling system is adopted to model and calculate the QUENCH-LOCA- 0 experiment. The correctness and validity of the flow blockage model are verified by comparing the peak cladding temperature. Finally, the DVI Line-SBLOCA accident is induced to analyze the influence of flow blockage on subsequent CAP1400 reactor core heat transfer and core degradation. From the results of the DVI Line-SBLOCA accident analysis, it can be concluded that the blockage ratio is in the range of 40%e60%, and the position of severe blockage is the same as that of cladding rupture. The blockage reduces the circulation area of the core coolant, which in turn impacts the heat exchange between the core and the coolant, leading to the early failure and collapse of some core assemblies and accelerating the core degradation process.