外商直接投资对安徽产业结构影响的实证分析

外商直接投资不仅为安徽带来了经济建设所急需的资金、技术和管理经验,创造了就业机会,增加了财政收入,还促进了安徽产业结构的升级。本文通过分布滞后模型分析了外商直接投资对安徽三大产业生产总值的效应,从而说明外商直接投资会对安徽产业结构产生影响。     

Asymptotic Formulas for Thermography Based Recovery of Anomalies

We start from a realistic half space model for thermal imaging, which we then use to develop a mathematical asymptotic analysis well suited for the design of reconstruction algorithms. We seek to reconstruct thermal anomalies only through their rough features. With this way our proposed algorithms are stable against measurement noise and geometry perturbations. Based on rigorous asymptotic estimates, we first obtain an approximation for the temperature profile which we then use to design nonit-erative detection algorithms. We show on numerical simulations evidence that they are accurate and robust. Moreover, we provide a mathematical model for ultrasonic temperature imaging, which is an important technique in cancerous tissue ablation therapy.AMS subject classifications: 35R20, 35B30     

Multilinear Exponential Sums in Prime Fields Under Optimal Entropy Condition on the Sources

The main result of this paper is an exponential sum bound in prime fields for multilinear expressions of the type under nearly optimal conditions on . It provides the expected generalization of the well-known inequality for r = 2. We also establish a new result on Gauss sums for multiplicative subgroups H of , obtaining a nontrivial estimate provided . This is a further improvement on [BGK]. Received: May 2007, Revision: October 2007, Accepted: October 2007     

Computing the Minkowski Sum of Prisms

Within this paper we study the Minkowski sum of prisms (“Cephoids”) in a finite dimensional vector space. For a vector with positive components we write and denote by the associated prism. We provide a representation of a finite sum of prisms in terms of inequalities. Dedicated to the 65th birthday of Alexander Rubinov.     

Free and nonfree Voronoi polyhedra

The Voronoi polyhedron of some point v of a translation lattice is the closure of the set of points in space that are closer to v than to any other lattice points. Voronoi polyhedra are a special case of parallelohedra, i.e., polyhedra whose parallel translates can fill the entire space without gaps and common interior points. The Minkowski sum of a parallelohedron with a segment is not always a parallelohedron. A parallelohedron P is said to be free along a vector e if the sum of P with a segment of the line spanned by e is a parallelohedron. We prove a theorem stating that if the Voronoi polyhedron P _v (f) of a quadratic form f is free along some vector, then the Voronoi polyhedron P _v (g) of each form g lying in the closure of the L-domain of f is also free along some vector. For the dual root lattice E ₆*, and the infinite series of lattices D _2m ⁺ , m ≥ 4, we prove that their Voronoi polyhedra are nonfree in all directions.     

一类亚纯函数项级数的留数算法

讨论在degQ-degP≥1条件下,有理函数项级数以及它与三角函数之积的亚纯函数项级数的和,得到它们的计算公式,并同时得到一些特殊和式的计算公式.     

Exponential sum estimates over subgroups and almost subgroups of \mathbb{Z}_{Q}^{*} , where Q is composite with few prime factors

In this paper we extend the exponential sum results from [BK] and [BGK] for prime moduli to composite moduli q involving a bounded number of prime factors. In particular, we obtain nontrivial bounds on the exponential sums associated to multiplicative subgroups H of size q^δ, for any given δ > 0. The method consists in first establishing a ‘sumproduct theorem’ for general subsets A of . If q is prime, the statement, proven in [BKT], expresses simply that either the sum-set A + A or the product-set A.A is significantly larger than A, unless |A| is near q. For composite q, the presence of nontrivial subrings requires a more complicated dichotomy, which is established here. With this sum-product theorem at hand, the methods from [BGK] may then be adapted to the present context with composite moduli. They rely essentially on harmonic analysis and graph-theoretical results such as Gowers’ quantitative version of the Balog–Szemeredi theorem. As a corollary, we get nontrivial bounds for the ‘Heilbronn-type’ exponential sums when q = p^r (p prime) for all r. Only the case r = 2 has been treated earlier in works of Heath-Brown and Heath-Brown and Konyagin (using Stepanov’s method). We also get exponential sum estimates for (possibly incomplete) sums involving exponential functions, as considered for instance in [KS]. Submitted: October 2004 Revision: June 2005 Accepted: August 2005     

Non-Moishezon twistor spaces of with non-trivial automorphism group

We show that a twistor space of a self-dual metric on with -isometry is not Moishezon iff there is a -orbit biholomorphic to a smooth elliptic curve, where the -action is the complexification of the -action on the twistor space. It follows that the -isometry has a two-sphere whose isotropy group is . We also prove the existence of such twistor spaces in a strong form to show that a problem of Campana and Kreußler is affirmative even though a twistor space is required to have a non-trivial automorphism group.

     

A sharp estimate for the rate of convergence in mean of Birkhoff sums for some classes of periodic differentiable functions

For a badly approximable vector α, we obtain a sharp estimate for the rate of convergence in the space L _p (0 < p < ∞) of the Birkhoff means $\frac{1}{n}\sum\nolimits_{s = 0}^{n = 1} {f(x + s\alpha )} $ for an absolutely continuous periodic function f and for functions in spaces of Bessel potentials.     

On the stability in periodic and almost periodic difference systems

In this paper we consider the system of difference equations