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Jieting Han,Yu Zhang,Shiyang Li,Bin Huang,Dazhuan Wu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.2
The effect of three noise reduction methods for rotor-stator interaction in diagonal flow fans was studied. The unsteady flow field and directivity of tonal noise were obtained by numerical simulation based on computational fluid dynamics (CFD) and the Ffowcs Williams and Hawkings (FW-H) method; the baseline model was tested in a semi-anechoic chamber. The generation mechanism and location of noise were investigated. In addition, the characteristics of tonal noise at blade-passing frequency (BPF) were studied, along with its harmonics. The results show that the tonal noise at 1 BPF dominates the overall sound pressure level. Proper rotor-stator spacing, a large forward-leaned angle, and a large backward-swept angle are beneficial to reduce tonal noise. Also, the noise reduction effect is related to the low amplitude and to the phase shift caused by the pressure response of the rotor wake impinging on stator surfaces, especially near the leading edge at 1 BPF.
ON QUASI-STABLE EXCHANGE IDEALS
Chen, Huanyin Korean Mathematical Society 2010 대한수학회지 Vol.47 No.1
We introduce, in this article, the quasi-stable exchange ideal for associative rings. If I is a quasi-stable exchange ideal of a ring R, then so is $M_n$(I) as an ideal of $M_n$(R). As an application, we prove that every square regular matrix over quasi-stable exchange ideal admits a diagonal reduction by quasi invertible matrices. Examples of such ideals are given as well.
ON QB-IDEALS OF EXCHANGE RINGS
Chen, Huanyin Korean Mathematical Society 2009 대한수학회보 Vol.46 No.5
We characterize QB-ideals of exchange rings by means of quasi-invertible elements and annihilators. Further, we prove that every $2\times2$ matrix over such ideals of a regular ring admits a diagonal reduction by quasi-inverse matrices. Prime exchange QB-rings are studied as well.
UNIT-REGULARITY AND STABLE RANGE ONE
Chen, Huanyin Korean Mathematical Society 2010 대한수학회보 Vol.47 No.3
Let R be a ring, and let $\Psi$(R) be the ideal generated by the set {x $\in$R | 1 + sxt $\in$ R is unit-regular for all s, t $\in$ R}. We show that $\Psi$(R) has "radical-like" property. It is proven that $\Psi$(R) has stable range one. Thus, diagonal reduction of matrices over such ideal is reduced.
ON QUASI-STABLE EXCHANGE IDEALS
Huanyin Chen 대한수학회 2010 대한수학회지 Vol.47 No.1
We introduce, in this article, the quasi-stable exchange ideal for associative rings. If I is a quasi-stable exchange ideal of a ring R, then so is Mn(I) as an ideal of Mn(R). As an application, we prove that every square regular matrix over quasi-stable exchange ideal admits a diagonal reduction by quasi invertible matrices. Examples of such ideals are given as well.
UNIT-REGULARITY AND STABLE RANGE ONE
Huanyin Chen 대한수학회 2010 대한수학회보 Vol.47 No.3
Let R be a ring, and let Ψ(R) be the ideal generated by the set {x ∈ R | 1 + sxt ∈ R is unit-regular for all s, t ∈ R}. We show that Ψ(R) has “radical-like” property. It is proven that Ψ(R) has stable range one. Thus, diagonal reduction of matrices over such ideal is reduced.
On QB-ideals of exchange rings
Huanyin Chen 대한수학회 2009 대한수학회보 Vol.46 No.5
We characterize QB-ideals of exchange rings by means of quasi-invertible elements and annihilators. Further, we prove that every 2×2 matrix over such ideals of a regular ring admits a diagonal reduction by quasi-inverse matrices. Prime exchange QB-rings are studied as well. We characterize QB-ideals of exchange rings by means of quasi-invertible elements and annihilators. Further, we prove that every 2×2 matrix over such ideals of a regular ring admits a diagonal reduction by quasi-inverse matrices. Prime exchange QB-rings are studied as well.