Sufficient conditions for the projective freeness of Banach algebras

Let R be a unital semi-simple commutative complex Banach algebra, and let M(R) denote its maximal ideal space, equipped with the Gelfand topology. Sufficient topological conditions are given on M(R) for R to be a projective free ring, that is, a ring in which every finitely generated projective R-module is free. Several examples are included, notably the Hardy algebra H^∞(X) of bounded holomorphic functions on a Riemann surface of finite type, and also some algebras of stable transfer functions arising in control theory.     

On a problem of Rolewicz about Banach spaces that admit support sets

We construct an example of a nonseparable Banach space which does not admit a support set.² It is a consistent (and necessarily independent from the axioms of ZFC) example of a space C(K) of continuous functions on a compact Hausdorff K with the supremum norm. The construction depends on a construction of a Boolean algebra with some combinatorial properties. The space is also hereditarily Lindelöf in the weak topology but it doesn't have any nonseparable subspace nor any nonseparable quotient which is a C(K) space for K dispersed.     

On Newton’s method for solving equations containing Fréchet-differentiable operators of order at least two

We provide sufficient conditions for the semilocal convergence of Newton’s method to a locally unique solution of a nonlinear operator equation containing operators that are Fréchet-differentiable of order at least two, in a Banach space setting. Numerical examples are also provided to show that our results apply to solve nonlinear equations in cases earlier ones cannot [J.M. Gutiérrez, A new semilocal convergence theorem for Newton’s method, J. Comput. Appl. Math. 79(1997) 131-145; Z. Huang, A note of Kantorovich theorem for Newton iteration, J. Comput. Appl. Math. 47 (1993) 211-217; F.A. Potra, Sharp error bounds for a class of Newton-like methods, Libertas Mathematica 5 (1985) 71-84].     

Lipschitz Estimates for Commutators of $N$-Dimensional Fractional Hardy Operators

In this paper, it is proved that the commutator$\mathcal{H}_{β,b}$ which is generated by the $n$-dimensional fractional Hardy operator $\mathcal{H}_β$ and $b\in \dot{Λ}_α(\mathbb{R}^n)$ is bounded from $L^P(\mathbb{R}^n)$ to $L^q(\mathbb{R}^n)$, where $0<α<1,1相似文献   

临近空间单粒子串扰的解析模型

随着尺寸不断缩减, 串扰对单粒子效应的影响越来越重要. 为了量化串扰效应对单粒子瞬态(SET)的影响, 基于SET等效电路和互连线的6 结点模型, 利用所定义的导纳的四种规则, 简化计算, 推导了单粒子串扰(SEC)的解析模型. 通过求导和泰勒公式, 导出了串扰电压峰值的表达式. 仿真结果显示, 该解析模型与SPICE电路的一致性较好, 平均相对误差为2.51%, 最大误差为5.11%.     

Coded transmissions for space links affected by solar scintillation: Baseband analysis

A thorough analysis of the behavior of error‐correcting codes over space links affected by solar scintillation is presented. The relevant channel parameters are fixed through the development of a model based on real missions' data. Both telecommand and telemetry links are considered in fast and slow fading conditions. Besides classical coherent modulation schemes, the possibility to use noncoherent modulation schemes is considered, to eliminate the problem of phase tracking. For the case of channels with very slow fading, the use of external interleavers or erasure coding is proposed to cope with error bursts.     

B值随机元阵列加权和的收敛性与大数定律

令｛Ｘｎｉ，１≤ｉ≤ｋｎ↑∞，ｎ≥１｝为Ｂ值随机元阵列，｛ａｎｉ，１≤ｉ≤ｋｎ，ｎ≥１｝为实数阵列．讨论加权和Ｓｎ＝ｋｎｉ＝１ａｎｉＸｎｉ，ｎ≥１的收敛性．在条件ｓｕｐｎ，ｉＰ（Ｘｎｉ＞ｘ）＝０（ｘ－ｒ）下给出了一些收敛性结果（１≤ｒ＜ｐ≤２），同时用这种收敛性刻划了Ｂａｎａｃｈ空间的ｐ型性质     

Cyclobutadiene dianion derivatives – Planar 4c,6e or three-dimensional 6c,6e aromaticity?

The spatial magnetic properties (Through Space NMR Shieldings – TSNMRS) of two cyclobutadiene derivatives (2 and 5) and of a number of cyclobutadiene dianion derivatives (3, 4 and 6–8) have been calculated by the GIAO perturbation method employing the Nucleus-Independent Chemical Shift (NICS) concept of P. v. Ragué Schleyer, and visualized as Iso-Chemical-Shielding Surfaces (ICSS) of various size and direction. TSNMRS values can be successfully employed to quantify and visualize the (anti)aromaticity of the compounds studied and to discuss the influence of Li⁺ complexation to cyclobutadiene dianion (4a, 7 and 8) on planar 4c,6e or three-dimensional 6c,6e aromaticity.     

AStudyontheInfluenceofCu￣2￣＋，Cd￣2￣＋andPb￣2￣＋onTripleHelixPoly（A：2I）

ＡＳｔｕｄｙｏｎｔｈｅＩｎｆｌｕｅｎｃｅｏｆＣｕ￣２￣＋,Ｃｄ￣２￣＋ａｎｄＰｂ￣２￣＋ｏｎＴｒｉｐｌｅＨｅｌｉｘＰｏｌｙ（Ａ：２Ｉ）￣＊ＨＵＡＥｒ－ｂｉｎｇａ￣ｂ￣,ＹＡＮＧＰｉｎ￣ｂ￣＊￣＊,ＬＩＱｉｎｇ－ｓｈａｎ￣ａ,ＹＡＮＧＢｉｎｇ－ｓｈｅｎ...