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AUTOMORPHISMS OF THE ZERO-DIVISOR GRAPH OVER 2 × 2 MATRICES
Ma, Xiaobin,Wang, Dengyin,Zhou, Jinming Korean Mathematical Society 2016 대한수학회지 Vol.53 No.3
The zero-divisor graph of a noncommutative ring R, denoted by ${\Gamma}(R)$, is a graph whose vertices are nonzero zero-divisors of R, and there is a directed edge from a vertex x to a distinct vertex y if and only if xy = 0. Let $R=M_2(F_q)$ be the $2{\times}2$ matrix ring over a finite field $F_q$. In this article, we investigate the automorphism group of ${\Gamma}(R)$.
Automorphisms of the zero-divisor graph over $2\times 2$ matrices
Xiaobin Ma,Dengyin Wang,Jinming Zhou 대한수학회 2016 대한수학회지 Vol.53 No.3
The zero-divisor graph of a noncommutative ring $R$, denoted by $\Gamma(R)$, is a graph whose vertices are nonzero zero-divisors of $R$, and there is a directed edge from a vertex $x$ to a distinct vertex $y$ if and only if $xy=0$. Let $R=M_{2}(F_q)$ be the $2\times 2$ matrix ring over a finite field $F_q$. In this article, we investigate the automorphism group of $\Gamma(R)$.
Coupling effects of vortex-induced vibration for a square cylinder at various angles of attack
Deqian Zheng,Wenyong Ma,Xiaobin Zhang,Wei Chen,Junhao Wu 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.34 No.5
Vortex-induced vibration (VIV) is a significant concern when designing slender structures with square cross sections. VIV strongly depends on structural dynamics and flow states, which depend on the conditions of the approaching flow and shape of a structure. Therefore, the effects of the angle of attack on the coupling effects of VIV for a square cylinder are expected to be significant in practice. In this study, the aerodynamic forces for a fixed and elastically mounted square cylinder were measured using wind pressure tests. Aerodynamic forces on the stationary cylinder are firstly discussed by comparisons of variation of statistical aerodynamic force and wind pressure coefficient with wind angle of attack. The coupling effect between the aerodynamic forces and the motion of the oscillating square cylinder by VIV is subsequently investigated in detail at typical wind angels of attack with occurrence of three typical flow regimes, i.e., leading-edge separation, separation bubble (reattachment), and attached flow. The coupling effect are illustrated by discussing the onset of VIV, characteristics of aerodynamic forces during VIV, and interaction between motion and aerodynamic forces. The results demonstrate that flow states can be classified based on final separation points or the occurrence of reattachment. These states significantly influence coupling effects of the oscillating cylinder. Vibration enhances vortex shedding, which creates strong fluctuations in aerodynamic forces. However, differences in the lock-in range, aerodynamic force, and interaction process for angles of attack smaller and larger than the critical angle of attack revealed noteworthy characteristics in the VIV of a square cylinder.
Rotordynamic characteristics of a novel pocket damper seal with self-regulated injection
Wanfu Zhang,Pengbo Qin,Xiaobin Zhang,Kai Ma,Lu Yin,Chun Li 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8
The conventional fully partitioned pocket damper seal (FPDS) was improved by introducing several nozzles on the first seal tooth, which generates a reverse injection fluid suppressing the cavity flow in the circumferential direction. Computational fluid dynamics (CFD) models of the conventional FPDS and current novel FPDS were established. An infinitesimal theory was employed to identify the rotordynamic coefficient of the FPDS. The influence of nozzle types (negative, straight, positive), inlet/outlet areas, deflection angles (θ) on the rotordynamic performance was comprehensively analyzed. It was found that reducing the circumferential flow in the first seal cavity is crucial for increasing the stability of the FPDS. A negative nozzle angle can restrict the circumferential flow effectively and significantly improve the effective damping and system stability. The crossover frequency for the novel FPDS with θ = -10° is ~62 Hz, which is much lower than that for the conventional FPDS (~85 Hz). The increasing inlet/outlet area ratio of the nozzle can also enhance the seal stability. Increasing the negative nozzle angle (θ = none, -10°, -15°, -20°) can effectively increase the effective damping and reduce the crossover frequency from ~85 Hz to ~38 Hz. However, the novel FPDS with three kinds of nozzles shows a slight increase (< 2.5 %) in the leakage flow rate compared with the conventional FPDS.
Jiping Liu,Shuyuan Wang,Liang Feng,Dongying Ma,Qiang Fu,Yu Song,Xiaobin Jia,Shiping Ma 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.7
Diabetic encephalopathy (DE) is one of the severe complications in patients with diabetes mellitus. Paeonol, an active compound isolated from the root bark of Paeonia suffruticosa, has significant antidiabetic activity in vivo. However, its underlying beneficial effects on DE were unclear. In the present study, the protective activity of paeonol on DE was evaluated in streptozotocin (STZ)-induced diabetic rats. Paeonol at 50 and 100mg/kg significantly increased body weight and decreased blood glucose levels, glycosylated serum proteins, and serum advanced glycation end products (AGEs) levels. Immunohistochemistry assays and Western blot analysis revealed a significant decrease in expressions on receptor for advanced glycation end products (RAGE) and nuclear factor kappa B (NF-jB) in hippocampus and cerebral cortical neurons after paeonol treatment. Furthermore, paeonol significantly increased glutathione content and remarkedly decreased induced nitric oxide synthase activity in hippocampus tissue. Our findings indicated that paeonol could improve the pathological damage of DE in STZ-induced diabetic rats. It might be associated with the modulating AGEs/RAGE/NF-jB pathway. This study suggested that paeonol might be a promising candidate for the prevention and treatment of DE.