A Field Calibration Method of Robotic Inspection System for Coating Thickness

Xiang WU,Tianfei CHEN 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

A coating thickness inspection system based on the serial robot has 6 domination of freedom (6 DoF) was proposed to improve the precision and convenience of the procedure of inspecting. The system consists of one functional part, two movement facilities and one central processing unit. The line-structured light sensor is the key part which is responsible for obtaining the strip image generated by the intersection of the structure light plane and the surface of the inspected work piece. The calibration method for this system contains two steps: Firstly, based on the particular designed 2D plane target and the known position information of the movement facilities, the parameters about the hand-eye relationship and camera in the sensor were calibrated. Then, the parameter of the laser plane was obtained via the principle of perspective three points and double cross ratio invariance. Only one auxiliary tools, the designed plane target is used for convenience on the field. Experiments showed that this system was accurate and efficient, besides which a coating thickness inspection system was implemented.

Robust Cooperative Relay Beamforming Design for Security

( Xiangwu Gong ),( Feihong Dong ),( Hongjun Li ),( Wei Shao ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.11

In this paper, we investigate a security transmission scheme at the physical layer for cooperative wireless relay networks in the presence of a passive eavesdropper. While the security scheme has been previously investigated with perfect channel state information(CSI) in the presence of a passive eavesdropper, this paper focuses on researching the robust cooperative relay beamforming mechanism for wireless relay networks which makes use of artificial noise (AN) to confuse the eavesdropper and increase its uncertainty about the source message. The transmit power used for AN is maximized to degrade the signal-to-interference-plus-noise-ratio (SINR) level at the eavesdropper, while satisfying the individual power constraint of each relay node and worst-case SINR constraint at the desired receiver under a bounded spherical region for the norm of the CSI error vector from the relays to the destination. Cooperative beamforming weight vector in the security scheme can be obtained by using S-Procedure and rank relaxation techniques. The benefit of the proposed scheme is showed in simulation results.

Applications of piezoelectric sensors in geotechnical engineering

Xiangwu Zeng 국제구조공학회 2006 Smart Structures and Systems, An International Jou Vol.2 No.3

Piezoelectric sensors have many applications in geotechnical engineering, especially in characterizing soils through measurement of wave velocities. Since mechanical properties of a material are closely associated with wave velocities, piezoelectric sensors provide a reliable and non-destructive method for the determination of soil properties. This paper presents results of recent research on measuring stiffness of a wide range of soils such as clay, sand, and gravel, characterizing anisotropic properties of soil induced by external loading, measuring stiffness of base and subgrade materials in the pavement, determining soil properties in a centrifuge model during the flight of a centrifuge, and understanding wave propagation in granular materials under micro-gravity environment using this technique.

Applications of piezoelectric sensors in geotechnical engineering

Zeng, Xiangwu Techno-Press 2006 Smart Structures and Systems, An International Jou Vol.2 No.3

Piezoelectric sensors have many applications in geotechnical engineering, especially in characterizing soils through measurement of wave velocities. Since mechanical properties of a material are closely associated with wave velocities, piezoelectric sensors provide a reliable and non-destructive method for the determination of soil properties. This paper presents results of recent research on measuring stiffness of a wide range of soils such as clay, sand, and gravel, characterizing anisotropic properties of soil induced by external loading, measuring stiffness of base and subgrade materials in the pavement, determining soil properties in a centrifuge model during the flight of a centrifuge, and understanding wave propagation in granular materials under micro-gravity environment using this technique.

Equivalence Analysis of Virtual Synchronous Machines and Frequency‑Droops for Inertia Emulation in Power Systems with Converter‑Interfaced Renewables

Weichao Zhang,Xiangwu Yan 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.3

In converter-based AC microgrids, the frequency-droop is widely applied. As a considerable share of installed capacity is replaced by renewable generation, the virtual synchronous machine (VSM) algorithm is presented to address stability issues caused by low-inertia converter interfaces. Recently, droop control loops are also modifed to improve stability. The VSM and the frequency-droop are both derived from the property imitation of synchronous generators (SGs) while researched independently. In this paper, by simplifcations in the steady state, the expression of the inertia emulation of the VSM algorithm based on the second-order SG model is linearized as a frst-order ordinary diferential equation. In frequency-droop loops, as the instantaneous power components are commonly passed through a low-pass flter for disturbance rejection, the system function of the droop control can also be transformed into a frst-order ordinary diferential equation, which is equivalent to that of the VSM under certain conditions. In terms of the inertia constant, the swing equation is normalized under per unit representation. By the same simplifcation in the VSM linearization, the equivalence between the linearized VSM and the SG is also demonstrated. Therefore, the equivalence among SGs, the VSM, and the frequency-droop are summarized, which provides insights for coordinative control of power converters integrated into current SG dominating power systems. For a specifc synchronous generator, the equivalence conditions are verifed by simulation.

On the chromaticity of the 2-degree integral subgraph of q-trees

Xiaodong Li,Xiangwu Liu 한국전산응용수학회 2007 Journal of applied mathematics & informatics Vol.25 No.1

ON THE CHROMATICITY OF THE 2-DEGREE INTEGRAL SUBGRAPH OF q-TREES

Li, Xiaodong,Liu, Xiangwu 한국전산응용수학회 2007 Journal of applied mathematics & informatics Vol.25 No.1

A graph G is called to be a 2-degree integral subgraph of a q-tree if it is obtained by deleting an edge e from an integral subgraph that is contained in exactly q - 1 triangles. An added-vertex q-tree G with n vertices is obtained by taking two vertices u, v (u, v are not adjacent) in a q-trees T with n - 1 vertices such that their intersection of neighborhoods of u, v forms a complete graph $K_{q}$, and adding a new vertex x, new edges xu, xv, $xv_{1},\;xv_{2},\;{\cdots},\;xv_{q-4}$, where $\{v_{1},\;v_{2},\;{\cdots},\;v_{q-4}\}\;{\subseteq}\;K_{q}$. In this paper we prove that a graph G with minimum degree not equal to q - 3 and chromatic polynomial $$P(G;{\lambda})\;=\;{\lambda}({\lambda}-1)\;{\cdots}\;({\lambda}-q+2)({\lambda}-q+1)^{3}({\lambda}-q)^{n-q-2}$$ with $n\;{\geq}\;q+2$ has and only has 2-degree integral subgraph of q-tree with n vertices and added-vertex q-tree with n vertices.

Hybrid Full Frequency Precoding for Integrated Remote Wireless Sensor and Multibeam Satellite Networks

( Hongjun Li ),( Feihong Dong ),( Xiangwu Gong ),( Changliang Deng ),( Luliang Jia ),( Jingchao Wang ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.6

This paper investigates an efficient transmission scheme for the remote wireless sensors to receive information which is rarely discussed in the integrated remote wireless sensor and multibeam satellite networks (IWSMSNs). The networks can be employed to exchange sensing information for emergency scenario, ocean scenario, and so on, which are isolated from available terrestrial networks. As the efficient transmission link is important to the IWSMSNs, we propose a hybrid full frequency (HFF) precoding by taking advantage of frequency reuse and multiple-input multiple-output (MIMO) precoding. Considering energy efficiency and sinks fairness are crucial to transmission link, thus the HFF precoding problems are formulated as transmit power minimization (TPM) and max-min fair (MMF) received signal to interference plus noise ratio (SINR) problems, which can be transformed to indefinite quadratic optimization programs. Then this paper presents a semi-definite programming (SDP) algorithm to solve the problems for the IWSMSNs. The promising potential of HFF for the real IWSMSNs is demonstrated through simulations.

Enhanced Reactive Dye Inkjet Printing Performance of Antimicrobial Silk Fabrics Surface Modified with Plasma and Chitosan

Yi Xu,Kuanjun Fang,Weichao Chen,Xiangwu Zhang,Chunming Zhang 한국섬유공학회 2022 Fibers and polymers Vol.23 No.9

This paper develops a new clean production technology combining atmospheric pressure plasma jets and nanochitosanto prepare strong and durable bio-based coatings for improving the inkjet printing performance of antimicrobial silkfabrics. The key contribution of this study is to introduce green and environmental friendly production methods, avoiding theuse of chemicals and pollution caused by dye hydrolysis in traditional ways. By contradistinctive experiments, we presentdirect empirical evidence that the plasma-chitosan treatment can significantly improve the hydrophilicity of the silk surfaces. Wettability test indicates that the infiltration time of droplet on the surface of modified silk fabric was only 1/12 of the timespent on the untreated sample. The study of reactive dye inkjet printing illustrates that the antibleeding property on modifiedsamples was evidently enhanced. Meanwhile, in respect of color fixation of reactive dyes, there was also an increase in K/Svalue on modified samples, ranging from 76 % to 214 % in color depth of the four-color print blocks, even after gas steamingand washing. Scanning electron microscope (SEM) observation reveals that the surface of silk fibers modified with plasma iscovered with firmer and more uniform chitosan coatings in terms of morphology change. X-ray photoelectron spectroscopy(XPS) analysis verifies that the content of oxygenous groups on the silk fabric processed by plasma-chitosan increased bymore than 42 %. As to the antibacterial effect of nano-chitosan, the photographs of inhibition zone shows that the plasmaprocessing effectively enhanced the durability of chitosan against B. subtilis, and thus prepared long-lasting antibacterial silkfabric. Furthermore, measurements of washing and rubbing color fastness prove that the plasma-chitosan treated fabrics stillhad excellent inkjet printing effect even after 45 cycles of soaping. Taken together, it turns out that such nontoxic,nonpolluting, low energy-consumed chitosan coating combining with plasma can explicitly provide an innovative option forthe production of inkjet printing on natural fabrics.

Hydrothermally synthesised NiCoP nanostructures and electrospun N-doped carbon nanofiber as multifunctional potential electrode for hybrid water electrolyser and supercapatteries

Surendran, Subramani,Shanmugapriya, Sathyanarayanan,Zhu, Pei,Yan, Chaoyi,Vignesh, Ramasamy Hari,Lee, Yun Sung,Zhang, Xiangwu,Selvan, Ramakrishnan Kalai Elsevier 2019 ELECTROCHIMICA ACTA Vol.296 No.-

<P><B>Abstract</B></P> <P>In this work, a facile single-step hydrothermal technique is used to prepare a spherically concomitant foamy NiCoP as positrode for supercapatteries. Similarly, the nitrogen-doped carbon nanofibers are prepared by simple electrospinning technique to use as negatrode. The prepared materials are raptly examined through primary studies for both energy conversion and storage applications. Fascinatingly, NiCoP electrode encourages oxygen evolution reaction, and the carbon nanofiber electrode emboldens hydrogen evolution reaction with the minimum overpotential of 257 mV and 160 mV, respectively. In addition, a supercapattery is designed and operated at a full voltage window of 1.6 V using the fusion of carbon nanofiber as the negatrode and the cutting-edge NiCoP as the positrode, which presents a superior energy (56 Wh kg<SUP>−1</SUP>) and an improved power density (5333 W kg<SUP>−1</SUP>) with a long cyclic stability (5000 cycles). Finally, the fabricated supercapattery device is used to power the constructed hybrid water electrolyser that requisites a low cell voltage of 1.71 V to afford a current density of 10 mA cm<SUP>−2</SUP>. Overall, the prepared electrodes reveal its superiority of handling the multifunctional challenges for both water electrolyzer and supercapatteries.</P>