Security Cooperation Model Based on Topology Control and Time Synchronization for Wireless Sensor Networks

Zhaobin Liu,Wenzhi Liu,Qiang Ma,Gang Liu,Liang Zhang,Ligang Fang,Victor S. Sheng 한국통신학회 2019 Journal of communications and networks Vol.21 No.5

To address malicious attacks generated from wirelesssensor networks (WSNs), in this paper, we study the difficulty ofdetecting uncoordinated behavior by using a model that is unreliableand has uncontrollable accuracy, trustless control, and an inextensibleprotocol. A security collaboration model involving coupledstate vectors associated with topology control and time synchronizationis proposed. The networks achieve synchronizationusing weights and by controlling the number of goals. The simplecalculation of time synchronization values between neighboringnodes serves as the basis for judging the behavior of the nodetopology control. The coupling state vector calculation is the coreof the model. The topology coupling strength rate, signal intensityreduction, clock drift, and clock delay are combined to form a comprehensivemodel. The network energy consumption is reduced byupdating the coupling state vector regularly. The coupling cooperationthreshold is set to make security decisions and effectivelydistinguish between attack nodes and dead nodes. Thus, to ensurethe security and reliability of the network, we present a securitycooperation collection tree protocol (SC-CTP) scheme that maintainsa trusted environment and isolates misbehaving nodes. Thesimulation results show that the model can detect malicious nodeseffectively, has a high detection rate, and greatly reduces the energyconsumption of the whole network. In order to verify the effectivenessof the proposed model, a large-scale wireless sensor networkwith 200 nodes was deployed on a campus. The proposed modelwas applied to optimize the deployment of key nodes on the campus. Furthermore, a candidate set of these nodes were selected toachieve coupling cooperation of key goals. This test verified the reliabilityof the model, its customizable accuracy, and the reliabilityof the control.

Study on modified differential transform method for free vibration analysis of uniform Euler-Bernoulli beam

Liu, Zhifeng,Yin, Yunyao,Wang, Feng,Zhao, Yongsheng,Cai, Ligang Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.5

A simulation method called modified differential transform is studied to solve the free vibration problems of uniform Euler-Bernoulli beam. First of all, the modified differential transform method is derived. Secondly, the modified differential transformation is applied to uniform Euler-Bernoulli beam free-free vibration. And then a set of differential equations are established. Through algebraic operations on these equations, we can get any natural frequency and normalized mode shape. Thirdly, the FEM is applied to obtain the numerical solutions. Finally, mode experimental method (MEM) is conducted to obtain experimental data for analysis by signal processing with LMS Test.lab Vibration testing and analysis system. Experimental data and simulation results are illustrated to be in comparison with the analytical solutions. The results show that the modified differential transform method can achieve good results in predicting the solution of such problems.

A facile, green synthesis of biomass carbon dots coupled with molecularly imprinted polymers for highly selective detection of oxytetracycline

Haochi Liu,Lan Ding,Ligang Chen,Yanhua Chen,Tianyu Zhou,Huiyu Li,Yuan Xu,Li Zhao,Ning Huang 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.69 No.-

Biomass carbon dots (CDs) prepared by sweet potato peels were superior fluorophores with low toxicity and excellent photostability. A novel designed fluorescence probe for specific recognition and sensitive detection of oxytetracycline (OTC) was fabricated with CDs and molecularly imprinted polymer (MIP). The quenching of CDs happened when rebinding with OTC due to electron-transfer-induced fluorescence quenching mechanism. The fluorescence probe was successfully applied in honey with the recoveries ranging from 90.2% to 97.3%. The detection limit of OTC was 15.3 ng mL−1. This work provides promising perspectives that the development of fluorescent MIP will be valuable for rapid analysis in complex samples.

Timoshenko beam-based stability and natural frequency analysis for heavy load mechanical spindles

Zhifeng Liu,Shiming Ma,Ligang Cai,Tieneng Guo,Yongsheng Zhao 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.11

The heavy load mechanical spindle is an important functional component in a 5-axis computer numerical control (CNC) machine tool,which is used to process large and complex free-form surfaces. It is necessary to obtain the natural frequency and analyze the spindle stability for improving the machining precision. In this paper, Timoshenko beam theory is introduced to model the mechanical spindle shaft, where the centrifugal force and gyroscopic effects are considered. Stability of the heavy load mechanical spindle shaft is analyzed,and the buckling load of the spindle shaft is obtained under different rotational speeds. The natural frequency of spindle is investigated in a freedom and restraint state, respectively. Comparing the proposed method with the simplified hollow cylinder and shaft prototype in the freedom state, the results show that they are highly correlated with experimental results. For the restraint state, the axial load, rotational speed, gyroscopic effect, and centrifugal force are discussed, and all of these parameters affect the natural frequency. The proposed modeling approach can be used for spindle design and optimization in a given machining process and can be easily extended to other spindle design.

Study on modified differential transform method for free vibration analysis of uniform Euler-Bernoulli beam

Zhifeng Liu,Yunyao Yin,Feng Wang,Yongsheng Zhao,Ligang Cai 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.5

A simulation method called modified differential transform is studied to solve the free vibration problems of uniform Euler-Bernoulli beam. First of all, the modified differential transform method is derived. Secondly, the modified differential transformation is applied to uniform Euler-Bernoulli beam freefree vibration. And then a set of differential equations are established. Through algebraic operations on these equations, we can get any natural frequency and normalized mode shape. Thirdly, the FEM is applied to obtain the numerical solutions. Finally, mode experimental method (MEM) is conducted to obtain experimental data for analysis by signal processing with LMS Test.lab Vibration testing and analysis system. Experimental data and simulation results are illustrated to be in comparison with the analytical solutions. The results show that the modified differential transform method can achieve good results in predicting the solution of such problems.

Synthesis and characterization of magnetic metal–organic framework for the adsorptive removal of Rhodamine B from aqueous solution

Haochi Liu,Xiaohui Ren,Ligang Chen 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.34 No.-

Adsorptive removal of Rhodamine B (RhB) on a novel kind of magnetic metal–organic framework (MOF)was studied in view of adsorption isotherm, thermodynamics and kinetics. The adsorbent wascharacterized by physical property measurement system, X-ray diffraction and scanning electronmicroscopy. The adsorption isotherm of RhB on magnetic MOF followed the Freundlich model. Theresultant kinetics data was well described by the pseudo-second-order model. Most of the RhB wasremoved from the aqueous solution within 30 min. Thermodynamic parameters including Gibbs freeenergy, enthalpy, and entropy of adsorption were obtained. The result confirmed that the adsorption iscontrolled by an entropy effect rather than an enthalpy change. The maximum removal has beenachieved in the pH range of 4–8 at 150 rpm. The sorbent can be used at least five times after washingwith methanol including HCl (0.001 mol L 1). The p p stacking interaction and electrostatic interactionmay play an important role in the adsorption of RhB onto magnetic MOF. Compared with otheradsorbents, this kind of magnetic material demonstrated a superior dye adsorption capability.

高师院校师范生师德培育的价值诉求、现实困境及优化路径

刘佳龙(Jialong Liu),姜立刚(Ligang Jiang) YIXIN 출판사 2024 Journal of Humanities and Social Sciences Vol.2 No.2

师德培育是高师院校师范生培育工作的核心要义,对深入贯彻立德树人的根本任务,满足新时代教师队伍建设,培养具有高尚道德情操的教师具有重要的现实价值。当前,高师院校师范生师德培育过程中面临着多元文化价值冲击、他律与自律二元对立、师德养成教育知行分离、师德养成评价模式固化的多元困境。要突破这些困境须以社会主义核心价值观为导向,引领师范生师德培育方向;以师德主体性建设为主线,内化师范生师德品质;以师德成长为培育路径,提升师范生师德水平;以多元化师德评价为基准,促进师范生师德养成。 The cultivation of teacher ethics is the core essence of the cultivation of normal college students. It has important practical value in deeply implementing the fundamental task of moral education, meeting the construction of the new era teacher team, and cultivating teachers with noble moral character. Currently, the process of cultivating teacher ethics among normal university students is facing multiple challenges, including the impact of multicultural values, the binary opposition between heteronomy and self-discipline, the separation of knowledge and action in teacher ethics education, and the solidification of teacher ethics evaluation models. To overcome these difficulties, we need to guide the direction of cultivating teacher ethics for normal students by the socialist core values, to take the construction of teacher ethics as the main line and internalizing the quality of teacher ethics among normal students, to take the growth of teacher ethics as the cultivation path to enhance the level of teacher ethics among teacher trainees and to use diversified teacher ethics evaluation as a benchmark to promote the cultivation of teacher ethics among normal students.

A nearly precise definition of fairness and a novel method for curve fairing

Xiaoguang Han,Ligang Liu,Guangchang Dong (사)한국CDE학회 2010 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8

Crystallographic Characterizations of Eutectic and Secondary Carbides in a Fe-12Cr-2.5Mo-1.5W-3V-1.25C Alloy

Jing Guo,Ligang Liu,Yunli Feng,Sha Liu,Xuejun Ren,Qingxiang Yang 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.2

In this work, the morphology and structures of the eutectic and secondary carbides in a new high chromiumFe-12Cr-2.5Mo-1.5W-3V-1.25C designed for cold-rolling work roll were systematically studied. The precipitatedcarbides inside the grains and along the grain boundaries were investigated with optical microscope,scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscopy andX-Ray diffraction. Selected area diffraction patterns have been successfully used to identify the crystal formationand lattice constants of the carbides with different alloying elements. The results show that the eutectic carbidesprecipitated contain MC and M2C distributed along the grain boundaries with dendrite feature. The compositionand crystal structure analysis shows that the eutectic MC carbides contain VC and WC with a cubic and hexagonalcrystal lattice structures respectively, while the eutectic M2C carbides predominantly contain V2C and Mo2Cwith orthorhombic and hexagonal crystal lattices respectively. The secondary carbides contain MC, M2C,M7C3 formed along the grain boundaries and their sizes are much larger than the eutectic carbides ones. The secondary M23C6 is much small (0.3-0.5μm) and is distributed dispersively inside the grain. Similar tothe eutectic carbides, the secondary carbides also contain VC, WC, V2C, and Mo2C. M7C3 is hexagonal(Fe,Cr)7C3, while M23C6 is indexed to be in a cubic crystal form.

Coral stone-inspired superwetting membranes with anti-fouling and self-cleaning properties for highly efficient oil–water separation

Wensong Ma,Ligang Lin,Jing Yang,Zitian Liu,Xinyang Li,Meina Xu,Xiaopeng Li,Chunhong Wang,Qingping Xin,Kongyin Zhao 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.120 No.-

Nowadays, the use of separation membranes to deal with oil–water emulsions has gained popularity. However, oil fouling of membrane surfaces during the separation of oil–water emulsion is still a significantchallenge. In this study, inspired by the biological coral stone structure, the gel layer was firmlyattached to the surface of membrane using a simple co-blending and cross-linking strategy. A superwettingmembrane (PVDF/CD-SA) with a coral stone structure was obtained. The PVDF/CD-SA membranehad a high permeate flux that was 4.2 times higher than that of the original membrane and a high separationefficiency of about 99.2 % for the separation of oil–water emulsion. Furthermore, the membranehad outstanding chemical stability. The fluxes of several different oil-in-water emulsions significantlyimproved, and the separation efficiencies were as high as 98 %. Moreover, the separation efficienciesand contact angles of the membrane remained unchanged after numerous cycles of use. The membraneexhibited excellent superhydrophilicity in air (instantaneous water wetting in air) and superoleophobicityunder water (underwater oil contact angle > 156). Most importantly, the oil was able to automaticallydetach from the surface of membrane, resulting in self-cleaning performance. Therefore, this PVDF/CD-SAmembrane eliminated the problem of oil adhesion, exhibiting excellent potential for practical applicationsin oil–water separation.