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Liu, Dajun,Wei, Jiaqun Korean Mathematical Society 2020 대한수학회보 Vol.57 No.4
We introduce the concept of S-exchange rings to unify various subclass of exchange rings, where S is a subset of the ring. Many properties on S-exchange rings are obtained. For instance, we show that a ring R is clean if and only if R is left U(R)-exchange, a ring R is nil clean if and only if R is left (N(R) - 1)-exchange, and that a ring R is J-clean if and only if R is left (J(R) - 1)-exchange. As a conclusion, we obtain a sufficient condition such that clean (nil clean property, respectively) can pass to corners and reprove that J-clean passes to corners by a different way.
Dajun Liu,Yaochuan Wang,Guiqiu Wang,Xixian Luo 한국광학회 2017 Current Optics and Photonics Vol.1 No.4
Based on the extended Huygens-Fresnel principle, the analytical propagation formulae for spectrallypartially coherent Gaussian Schell-model pulsed (SPGSMP) beams propagating in turbulent atmospherehave been derived. The influences of the parameters for turbulent atmosphere and SPGSMP beams onthe on-axis and off-axis spectral shift and degree of coherence for SPGSMP beams propagating in turbulentatmosphere have been analyzed, using numerical calculations. The obtained results have potential applicationsfor SPGSMP beams in free-space optical communication and laser lidar.
Spreading of a Lorentz-Gauss vortex beam propagating through oceanic turbulence
Dajun Liu,Hongming Yin,Guiqiu Wang,Yaochuan Wang 한국광학회 2019 Current Optics and Photonics Vol.3 No.2
Based on the extended Huygens-Fresnel principle, the analytical equation for a Lorentz-Gauss vortex beam propagating through oceanic turbulence has been derived. The spreading properties of a Lorentz-Gauss vortex beam propagating through oceanic turbulence are analyzed in detail using numerical examples. The results show that a Lorentz-Gauss vortex beam propagating through stronger oceanic turbulence will spread more rapidly, and the Lorentz-Gauss vortex beam with higher topological charge M will lose its initial dark center more slowly.
Dajun Liu,Guiqiu Wang,Xixian Luo,Hongming Yin,Yaochuan Wang 한국광학회 2016 Current Optics and Photonics Vol.20 No.6
The analytical expressions for a partially coherent flat-topped vortex hollow beam propagating in uniaxialcrystals orthogonal to the optical axis are derived, and the intensity and coherent vortex properties ofpartially coherent flat-topped vortex hollow beam propagation in uniaxial crystals orthogonal to the opticalaxis are analyzed by numerical examples. The influence of beam order parameter N, topological chargeM, the coherence length and the ratio of refractive indices ne/no of uniaxial crystals on the normalizedintensity distribution and coherent vortex of a partially coherent flat-topped vortex hollow beam propagatingin uniaxial crystals are discussed in detail.
Dajun Liu,Yaochuan Wang,Guiqiu Wang,Hongming Yin 한국광학회 2016 Current Optics and Photonics Vol.20 No.1
Using coherence theory, the partially coherent flat-topped vortex hollow beam is introduced. The analyticalequation for propagation of a partially coherent flat-topped vortex hollow beam in turbulent atmosphereis derived, using the extended Huygens-Fresnel diffraction integral formula. The influence of coherencelength, beam order N, topological charge M, and structure constant of the turbulent atmosphere on theaverage intensity of this beam propagating in turbulent atmosphere are analyzed using numerical examples.
Homological properties of semi-Wakamatsu-tilting modules
Dajun Liu,Jiaqun Wei 대한수학회 2020 대한수학회보 Vol.57 No.3
For a fixed semi-Wakamatsu-tilting module $_{A}T$, we generalize the concepts of Auslander class, Bass class, and investigate many homological properties of such classes. Moreover, we establish an equivalence between the class of $\infty$-$T$-cotorsionfree modules and a subclass of the class of $T$-adstatic modules. Finally, a similar version of Auslander-Bridger approximation theorem and a nice property of relative cotranspose are obtained.
HOMOLOGICAL PROPERTIES OF SEMI-WAKAMATSU-TILTING MODULES
Liu, Dajun,Wei, Jiaqun Korean Mathematical Society 2020 대한수학회보 Vol.57 No.3
For a fixed semi-Wakamatsu-tilting module <sub>A</sub>T, we generalize the concepts of Auslander class, Bass class, and investigate many homological properties of such classes. Moreover, we establish an equivalence between the class of ∞-T-cotorsionfree modules and a subclass of the class of T-adstatic modules. Finally, a similar version of Auslander-Bridger approximation theorem and a nice property of relative cotranspose are obtained.
Dajun Liu,Jiaqun Wei 대한수학회 2020 대한수학회보 Vol.57 No.4
We introduce the concept of $S$-exchange rings to unify various subclass of exchange rings, where $S$ is a subset of the ring. Many properties on $S$-exchange rings are obtained. For instance, we show that a ring $R$ is clean if and only if $R$ is left $U(R)$-exchange, a ring $R$ is nil clean if and only if $R$ is left $(N(R)-1)$-exchange, and that a ring $R$ is $J$-clean if and only if $R$ is left $(J(R)-1)$-exchange. As a conclusion, we obtain a sufficient condition such that clean (nil clean property, respectively) can pass to corners and reprove that $J$-clean passes to corners by a different way.
Chang Liu,Xiaoxu Yang,Zhishan Yan,Youjun Fan,Guojun Feng,Dajun Liu 한국유전학회 2019 Genes & Genomics Vol.41 No.12
and quality. At present, little is known about the genes and molecular regulation mechanism in cold response in snap bean exposed to low temperature. Objectives Our objectives were to identify the low temperature response genes in snap bean and to examine differences in the gene response between cold-tolerant and cold-sensitive genotypes. Methods We used two highly inbred snap bean lines in this study, the cold-tolerant line ‘120’, and the cold-sensitive line ‘093’. The plants were grown to the three leaf and one heart stage and exposed to 4 °C low temperature. We used RNA sequencing (RNA-seq) to analyze the differences of gene expression. Results 988 and 874 cold-responsive genes were identified in ‘T120 vs CK120’ and ‘T093 vs CK093’ (‘T’ stands for low temperature treatment, and ‘CK’ stands for control at room temperature), respectively. Of these, 555 and 442 genes were unique to cold-stressed lines ‘120’ and ‘093’, respectively compared to the control. Our analysis of these differentially expressed genes indicates that Ca2+, ROS, and hormones act as signaling molecules that play important roles in low temperature response in P. vulgaris. Altering the expression of genes in these signaling pathways activates expression of downstream response genes which can interact with other signaling regulatory networks. This may maintained the balance of ROS and hormones, making line ‘120’ more cold-tolerant than line ‘093’. Conclusion Our results provide a preliminarily understanding of the molecular basis of low temperature response in snap bean, and also establish a foundation for the future genetic improvement of cold sensitivity in snap bean by incorporating genes for cold tolerance.
( Xiyao Liu ),( Yu Ge ),( Yuesheng Zhu ),( Dajun Wu ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.12
Integrity authentication of biometric data in Wireless Body Area Network (WBAN) is a critical issue because the sensitive data transmitted over broadcast wireless channels could be attacked easily. However, traditional cryptograph-based integrity authentication schemes are not suitable for WBAN as they consume much computational resource on the sensor nodes with limited memory, computational capability and power. To address this problem, a novel lightweight integrity authentication scheme based on reversible watermark is proposed for WBAN and implemented on a TinyOS-based WBAN test bed in this paper. In the proposed scheme, the data is divided into groups with a fixed size to improve grouping efficiency; the histogram shifting technique is adopted to avoid possible underflow or overflow; local maps are generated to restore the shifted data; and the watermarks are generated and embedded in a chaining way for integrity authentication. Our analytic and experimental results demonstrate that the integrity of biometric data can be reliably authenticated with low cost, and the data can be entirely recovered for healthcare applications by using our proposed scheme.