Image Edge Detection Based on Anti-Symmetrical Biorthogonal Wavelet Filter Banks with the Same Even Length

Xiaoyan Wang,Baochen Jiang,Chengyou Wang,Zhiqiang Yang,Xiaoyan Wang 보안공학연구지원센터 2014 International Journal of Signal Processing, Image Vol.7 No.5

With the development of the theory of wavelet transform, biorthogonal wavelet filter banks with linear phase and compact support characteristics are widely used in signal and image processing. We study the multiscale edge detection using anti-symmetrical biorthogonal wavelet filter banks with the same even length based on the analysis of the properties of this wavelet filter banks. The steps of multiscale edge detection based on anti-symmetrical biorthogonal wavelet are introduced in detail. Experimental results on test images show that compared with the anti-symmetrical biorthogonal wavelet, the proposed anti-symmetrical biorthogonal wavelet filter banks with the same even length have better performance in terms of image edge detection. Therefore, the anti-symmetrical biorthogonal wavelet filter banks with the same even length are more suitable for image edge detection.

An Optimized Third Harmonic Injection Method for Three-Phase Cascaded H-Bridge Photovoltaic Inverter

Wang Mao,Xing Zhang,Tao Zhao,Yuhua Hu,Fusheng Wang,Zhiqiang Dai,Renxian Cao 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

The uneven irradiation and temperature in photovoltaic (PV) modules of three-phase cascaded H-bridge (CHB) inverters will cause the unbalanced output power between solar panels, resulting in unbalanced grid current between three phases. In addition, since each phase can be regarded as a single-phase inverter, the second harmonic voltage pulsation of dc-side capacitors is a problem to be solved. To solve these two problems, a third harmonic injection optimization method on the basis of fundamental frequency zero sequence is proposed in this paper. The third harmonic with the same amplitude of fundamental modulated wave signal is injected into the modulated wave signal when the amplitude of synthesized wave signal is no greater than unity. Otherwise, the amplitude of third harmonic is decreased correspondingly to ensure the amplitude of synthesized wave signal being unity. With this method, the dc-side voltage pulsation is effectively restrained and the power balancing limit of CHB inverter is expanded. The feasibility and effectiveness of this method are verified by an experimental prototype of a three-phase seven-level CHB inverter.

RPFuzzer: A Framework for Discovering Router Protocols Vulnerabilities Based on Fuzzing

( Zhiqiang Wang ),( Yuqing Zhang ),( Qixu Liu ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.8

How to discover router vulnerabilities effectively and automatically is a critical problem to ensure network and information security. Previous research on router security is mostly about the technology of exploiting known flaws of routers. Fuzzing is a famous automated vulnerability finding technology; however, traditional Fuzzing tools are designed for testing network applications or other software. These tools are not or partly not suitable for testing routers. This paper designs a framework of discovering router protocol vulnerabilities, and proposes a mathematical model Two-stage Fuzzing Test Cases Generator(TFTCG) that improves previous methods to generate test cases. We have developed a tool called RPFuzzer based on TFTCG. RPFuzzer monitors routers by sending normal packets, keeping watch on CPU utilization and checking system logs, which can detect DoS, router reboot and so on. RPFuzzer` debugger based on modified Dynamips, which can record register values when an exception occurs. Finally, we experiment on the SNMP protocol, find 8 vulnerabilities, of which there are five unreleased vulnerabilities. The experiment has proved the effectiveness of RPFuzzer.

Strategic Fit Issues in Information System Research : Concept, Operationalization and Future Directions

Zhiqiang Wang 보안공학연구지원센터 2014 International Journal of Hybrid Information Techno Vol.7 No.1

Layer speciation and electronic structure investigation of freestanding hexagonal boron nitride nanosheets.

Wang, Jian,Wang, Zhiqiang,Cho, Hyunjin,Kim, Myung Jong,Sham, T K,Sun, Xuhui RSC Pub 2015 Nanoscale Vol.7 No.5

<P>Chemical imaging, thickness mapping, layer speciation and polarization dependence have been performed on single and multilayered (up to three layers and trilayered nanosheets overlapping to form 6 and 9 layers) hexagonal boron nitride (hBN) nanosheets by scanning transmission X-ray microscopy. Spatially-resolved XANES directly from freestanding regions of different layers has been extracted and compared with sample normal and 30 tilted configurations. Notably a double feature σ* excitonic state and a stable high energy σ* state were observed at the boron site in addition to the intense π* excitonic state. The boron projected σ* DOS, especially the first σ* exciton, is sensitive to surface modification, particularly in the single layered hBN nanosheet which shows more significant detectable contaminants and defects such as tri-coordinated boron/nitrogen oxide. The nitrogen site has shown very weak or no excitonic character. The distinct excitonic effect on boron and nitrogen was interpreted to the partly ionic state of hBN. Bulk XANES of hBN nanosheets was also measured to confirm the spectro-microscopic STXM result. Finally, the unoccupied electronic structures of hBN and graphene were compared.</P>

Advances in CRISPR-Cas systems for RNA targeting, tracking and editing

Wang, Fei,Wang, Lianrong,Zou, Xuan,Duan, Suling,Li, Zhiqiang,Deng, Zixin,Luo, Jie,Lee, Sang Yup,Chen, Shi Elsevier 2019 BIOTECHNOLOGY ADVANCES Vol.37 No.5

<P><B>Abstract</B></P> <P>Clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein (Cas) systems, especially type II (Cas9) systems, have been widely used in gene/genome targeting. Modifications of Cas9 enable these systems to become platforms for precise DNA manipulations. However, the utilization of CRISPR-Cas systems in RNA targeting remains preliminary. The discovery of type VI CRISPR-Cas systems (Cas13) shed light on RNA-guided RNA targeting. Cas13d, the smallest Cas13 protein, with a length of only ~930 amino acids, is a promising platform for RNA targeting compatible with viral delivery systems. Much effort has also been made to develop Cas9, Cas13a and Cas13b applications for RNA-guided RNA targeting. The discovery of new RNA-targeting CRISPR-Cas systems as well as the development of RNA-targeting platforms with Cas9 and Cas13 will promote RNA-targeting technology substantially. Here, we review new advances in RNA-targeting CRISPR-Cas systems as well as advances in applications of these systems in RNA targeting, tracking and editing. We also compare these Cas protein-based technologies with traditional technologies for RNA targeting, tracking and editing. Finally, we discuss remaining questions and prospects for the future.</P> <P><B>Highlights</B></P> <P> <UL> <LI> RNA targeting and editing are becoming increasingly important </LI> <LI> CRISPR-Cas systems are advancing for RNA targeting, tracking and editing </LI> <LI> The type VI CRISPR-Cas systems are useful for RNA-guided RNA targeting </LI> <LI> Use of Cas9 and Cas13 will advance RNA-targeting technologies </LI> </UL> </P>

Pistafolin B is the major aldose reductase inhibitor of the pods of tara [<i>Caesalpinia spinose</i> (Molina) Kuntze]

Wang, Zhiqiang,Guillen Quispe, Yanymee N.,Hwang, Seung Hwan,Zuo, Guanglei,Lim, Soon Sung Elsevier 2018 Industrial crops and products Vol.122 No.-

<P><B>Abstract</B></P> <P>Aldose reductase, the pivotal enzyme in the polyol pathway, has been widely investigated as an enzyme critically involved in the onset and progression of various pathologies associated with diabetes mellitus. Investigation of the inhibitory effect of tara [<I>Caesalpinia spinosa</I> (Molina) Kuntze] pods extract on aldose reductase revealed that its <I>n</I>-butanol fraction exhibits excellent aldose reductase inhibitory activity <I>in vitro</I> and <I>ex vivo</I>. Methyl gallate and pistafolin B were isolated from the <I>n</I>-butanol fraction of the tara pod methanolic extract as the main contributors for its aldose reductase inhibition, guided by affinity-based ultrafiltration-high performance liquid chromatography, with pistafolin B being the more potent inhibitor of the two. <I>In vitro</I> and <I>in silico</I> results demonstrated that pistafolin B is a mixed-type inhibitor that can bind to the aldose reductase active site rapidly, preventing substrate access and product formation (IC<SUB>50</SUB>, 0.198 mM; <I>K</I> <SUB>i</SUB>, 0.34 mM). <I>Ex vivo</I> experiments indicated that pistafolin B can penetrate the eye lens and successfully inhibit aldose reductase under hyperglycaemic conditions, thus preventing the accumulation of sorbitol and the subsequent osmotic stress.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The inhibitory effects of tara pods on aldose reductase activity were investigated. </LI> <LI> <I>n</I>-Butanol fraction of tara pods extract showed best aldose reductase inhibition. </LI> <LI> Aldose reductase ultrafiltration-high pressure liquid chromatography was developed. </LI> <LI> Pistafolin B was identified as a novel aldose reductase inhibitor in tara pods. </LI> </UL> </P>

A New Three-Phase Current Modulation Method to Suppress the Commutation Torque Ripple of Brushless DC Motor

Zhiqiang Wang,Shuai Yin,Tiehua Ma 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.5

The brushless DC motor’s commutation torque ripple is caused by inconsistency in the rate of phase current change. Thus, a method that considers armature resistance is proposed to modulate phase current. The three-phase control strategy, which involves the “open-phase conduction, off-phase pulse width modulation, and maintained non-commutation phase” technique, is applied during commutation at full-speed segments of the motor. Changes in each phase current are analyzed theoretically by establishing mathematical model based on phase current to determine the relative difference among shutdown phase, duty, and motor operating parameters. The turn-on and turn-off phase current change rates are made to be consistent to ensure less non-commutation phase current ripple, then the torque ripple is inhibited. The simulation results show that the phase commutation current and torque ripple coefficient of the proposed method are reduced from 56.9% and 55.5% to 6.8% and 6.1%, respectively. In the experiment system, the pulsation coefficient of the motor phase current is reduced from 40.0% to 16.7% at low speed and 50.0% to 18.8% at high speed. The simulation and experimental results show that the proposed control method significantly inhibits commutation current and torque in the full section.

Seismic Response Analysis of Self-anchored Suspension Bridge with Multi-tower

Zhiqiang Wang,Wei Xiao,Hongyi Wei 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.4

Seismic performance of a self-anchored suspension bridge with three-tower were investigated. A three-dimensional nonlinear finite element model of the bridge was developed using Sap2000. Nonlinear time history analysis was conducted using Fast Nonlinear Analysis Method (FNA), while beam-column effect and nonlinear behavior of bearing and damper were taken into consideration. The analyze results showed that the middle tower was more vulnerable compared with the two side towers; there existed risk of buckling of composite beam, and the most vulnerable part lied near steel-concrete composite segment. Viscous dampers were effective to reduce seismic response of towers as well as girders.

A New Three-Phase Current Modulation Method to Suppress the Commutation Torque Ripple of Brushless DC Motor

Wang, Zhiqiang,Yin, Shuai,Ma, Tiehua The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.5

The brushless DC motor's commutation torque ripple is caused by inconsistency in the rate of phase current change. Thus, a method that considers armature resistance is proposed to modulate phase current. The three-phase control strategy, which involves the "open-phase conduction, off-phase pulse width modulation, and maintained non-commutation phase" technique, is applied during commutation at full-speed segments of the motor. Changes in each phase current are analyzed theoretically by establishing mathematical model based on phase current to determine the relative difference among shutdown phase, duty, and motor operating parameters. The turn-on and turn-off phase current change rates are made to be consistent to ensure less non-commutation phase current ripple, then the torque ripple is inhibited. The simulation results show that the phase commutation current and torque ripple coefficient of the proposed method are reduced from 56.9% and 55.5% to 6.8% and 6.1%, respectively. In the experiment system, the pulsation coefficient of the motor phase current is reduced from 40.0% to 16.7% at low speed and 50.0% to 18.8% at high speed. The simulation and experimental results show that the proposed control method significantly inhibits commutation current and torque in the full section.