Primitive polynomial with three coefficients prescribed

The authors proved in Fan and Han (Finite Field Appl., in press) that, for any given (a₁,a₂,a₃)F_q³, there exists a primitive polynomial f(x)=xⁿ−σ₁xⁿ⁻¹++(−1)ⁿσ_n over F_q of degree n with the first three coefficients σ₁,σ₂,σ₃ prescribed as a₁,a₂,a₃ when n8. But the methods in Fan and Han (in press) are not effective for the case of n=7. Mills (Existence of primitive polynomials with three coefficients prescribed, J. Algebra Number Theory Appl., in press) resolves the n=7 case for finite fields of characteristic at least 5. In this paper, we deal with the remaining cases and prove that there exists a primitive polynomial of degree 7 over F_q with the first three coefficient prescribed where the characteristic of F_q is 2 or 3.     

主左理想由若干个幂等元生成的环

环Ｒ称为左ＰＩ－环，是指Ｒ的每个主左理想由有限个幂等元生成．本文的主要目的是研究左ＰＩ－环的ｖｏｎ Ｎｅｕｍａｎｎ正则性，证明了如下主要结果：（１）环Ｒ是Ａｒｔｉｎ半单的当且仅当Ｒ是正交有限的左ＰＩ－环；（２）环Ｒ是强正则的当且仅当Ｒ是左ＰＩ－环，且对于Ｒ的每个素理想Ｐ，Ｒ／Ｐ是除环；（３）环Ｒ是正则的且Ｒ的每个左本原商环是Ａｒｔｉｎ的当且仅当Ｒ是左ＰＩ－环且Ｒ的每个左本原商环是Ａｒｔｉｎ的；（４）环Ｒ是左自内射正则环且Ｓｏｃ（_ＲＲ）≠０当且仅当Ｒ是左ＰＩ－环且它包含内射极大左理想；（５）环Ｒ是ＭＥＬＴ正则环当且仅当Ｒ是ＭＥＬＴ左ＰＩ－环．     

A note on Hensel's lemma in several variables

The standard hypotheses for Hensel's Lemma in several variables are slightly stronger than necessary, in the case that the Jacobian determinant is not a unit. This paper shows how to weaken the hypotheses for Hensel's Lemma and some related theorems.

     

Progressive construction of an “Olympic” gel

We consider a melt of cyclic polymers (N monomers per chain) containing a small volume fraction ϕ of open cycles (P monomers per chain, with P< N) with reactive ends. The reaction leads to the formation of small P-rings. If these P-rings trap a sufficient number ofN-rings, a macroscopic cluster (“Olympic” gel) will appear. Using a very primitive theory (where the statistics of knots is replaced by a statistics of proximity), we expect gelation to occur when ϕ > max P^1/2/N,(1/N) exp(const/P). Our study is restricted to N-rings that are small enough for their conformations to be Gaussian.     

牛顿环实验数据的采集与处理

利用CCD采集牛顿环干涉图样数据，使用自编软件对数据进行处理，根据干涉图样中心坐标计算出了透镜曲率半径。     

Stability of small fullerenes C n (n=36,40 and 60): A topological and molecular orbital approach

Summary By semi-empirical molecular orbital calculations stability of fullerenes was analyzed in terms of topological parameters, such as the number of special fragments and the number of three types of abutting bonds between two 5-membered rings. Relative stability was compared by AM1 method for all spectrally distinct closed-shell isomers of C₃₆ and C₄₀ fullerenes, and for some closed-shell isomers of C₆₀ fullerene. Molecular geometries of these fullerenes were also optimized. Their relative stabilities were well explained by the instability of abutting bonds.     

The Weierstrass semigroup of a pair of GaloisWeierstrass points with prime degree on a curve

We describe the Weierstrass semigroup of a Galois Weierstrass point with prime degree and the Weierstrass semigroup of a pair of Galois Weierstrass points with prime degree, where a Galois Weierstrass point with degree n means a total ramification point of a cyclic covering of the projective line of degree n.*Supported by Korea Research Foundation Grant (KRF-2003-041-C20010).**Partially supported by Grant-in-Aid for Scientific Research (15540051), JSPS.     

Co-current flow effects on a rising Taylor bubble

The effects of co-current flows on a rising Taylor bubble are systematically investigated by a front tracking method coupled with a finite difference scheme based on a projection approach. Both the upward (the co-current flows the same direction as the buoyancy force) and the downward (the co-current moves in the opposite direction of the buoyancy force) co-currents are examined. It is found that the upward co-current tends to elongate the bubble, while the downward co-current makes the bubble fatter and shorter. For large N_f (the inverse viscosity number), the upward co-current also elongates the skirted tail and makes the tail oscillate, while the downward co-current shortens the tail and even changes a dimpled bottom to a round shape. The upward co-current promotes the separation at the tail, while the downward co-current suppresses the separation. The terminal velocity of the Taylor bubble rising in a moving flow is a linear combination of the mean velocity (U_C) of the co-current and the terminal velocity (U₀) of the bubble rising in the stagnant liquid, and the constant is around 2 which agrees with the literature. The wake length is linearly proportional to the velocity ratio (U_C/U₀). The co-currents affect the distribution of the wall shear stresses near the bubble, but not the maximum.