Extending path computation element for lightpath restoration in wavelength-switched optical networks

<正>Current generalized multi-protocol label switching(GMPLS) standards do not include adequate models for wavelength-switched optical networks(WSON) in recovery mechanisms.In this letter,GMPLS/path computation element(PCE) extensions are applied for the restoration of the lightpaths disrupted by collision or optical impairment.A reserved deflection routing scheme is proposed to achieve fast restoration. It uses the expanded PCE component to compute and assign the backup paths for lightpath recovery. Numerical results demonstrate that this scheme is effective and low cost.     

A MAP/G/1 Queue with Negative Customers

In this paper, we consider a MAP/G/1 queue with MAP arrivals of negative customers, where there are two types of service times and two classes of removal rules: the RCA and RCH, as introduced in section 2. We provide an approach for analyzing the system. This approach is based on the classical supplementary variable method, combined with the matrix-analytic method and the censoring technique. By using this approach, we are able to relate the boundary conditions of the system of differential equations to a Markov chain of GI/G/1 type or a Markov renewal process of GI/G/1 type. This leads to a solution of the boundary equations, which is crucial for solving the system of differential equations. We also provide expressions for the distributions of stationary queue length and virtual sojourn time, and the Laplace transform of the busy period. Moreover, we provide an analysis for the asymptotics of the stationary queue length of the MAP/G/1 queues with and without negative customers.     

Censoring,Factorizations, and Spectral Analysis for Transition Matrices with Block-Repeating Entries

In this paper, we use the Markov chain censoring technique to study infinite state Markov chains whose transition matrices possess block-repeating entries. We demonstrate that a number of important probabilistic measures are invariant under censoring. Informally speaking, these measures involve first passage times or expected numbers of visits to certain levels where other levels are taboo; they are closely related to the so-called fundamental matrix of the Markov chain which is also studied here. Factorization theorems for the characteristic equation of the blocks of the transition matrix are obtained. Necessary and sufficient conditions are derived for such a Markov chain to be positive recurrent, null recurrent, or transient based either on spectral analysis, or on a property of the fundamental matrix. Explicit expressions are obtained for key probabilistic measures, including the stationary probability vector and the fundamental matrix, which could be potentially used to develop various recursive algorithms for computing these measures.     

Stationary distributions for two-dimensional sticky Brownian motions: Exact tail asymptotics and extreme value distributions

Sticky Brownian motions can be viewed as time-changed semimartingale reflecting Brownian motions, which find applications in many areas including queueing theory and mathematical finance. In this paper,we focus on stationary distributions for sticky Brownian motions. Main results obtained here include tail asymptotic properties in the marginal distributions and joint distributions. The kernel method, copula concept and extreme value theory are the main tools used in our analysis.     

Affine flag varieties and quantum symmetric pairs,II. Multiplication formula

We establish a multiplication formula for a tridiagonal standard basis element in the idempotent version, i.e., the Lusztig form, of the coideal subalgebras of quantum affine ${\mathfrak{gl}}_n$ arising from the geometry of affine partial flag varieties of type C. We apply this formula to obtain the stabilization algebras ${\dot{\mathbf{K}}}_n^{\mathfrak{c}}$, ${\dot{\mathbf{K}}}_{\mathfrak{n}}^{??}$, ${\dot{\mathbf{K}}}_{\mathfrak{n}}^{??}$ and ${\dot{\mathbf{K}}}_{\eta }^{??}$, which are idempotented coideal subalgebras of quantum affine ${\mathfrak{gl}}_n$. The symmetry in the formula leads to an isomorphism of the idempotented coideal subalgebras ${\dot{\mathbf{K}}}_{\mathfrak{n}}^{??}$ and ${\dot{\mathbf{K}}}_{\mathfrak{n}}^{??}$ with compatible monomial, standard and canonical bases.     

Strong cleanness of generalized matrix rings over a local ring

Let K_s(R) be the generalized matrix ring over a ring R with multiplier s. For a general local ring R and a central element s in the Jacobson radical of R, necessary and sufficient conditions are obtained for K_s(R) to be a strongly clean ring. For a commutative local ring R and an arbitrary element s in R, criteria are obtained for a single element of K_s(R) to be strongly clean and, respectively, for the ring K_s(R) to be strongly clean. Specializing to s = 1 yields some known results. New families of strongly clean rings are presented.     

大跨预应力混凝土桥梁极限承载力计算

针对大跨预应力混凝土桥梁极限承载力的计算问题,提出建立在三维实体退化虚拟层合单元理论基础上同时考虑结构双重非线性的空间分析计算方法,并对大跨预应力混凝土桥梁极限承载力计算中的一些关键问题进行了探索研究,包括三维空间预应力效应的模拟;成桥内力的正确考虑;正确计及加载历史等。最后以一座典型的预应力混凝土连续刚构桥为例,给出了其具体的计算结果。分析表明,本文为考虑空间效应和破坏形态的大跨预应力混凝土桥梁全桥极限承载力分析提供了一种合理有效的途径,且计算方法具有很强的通用性。     

Wavelength pre-assignment collision schedule for wavelength-routed optical networks

A novel wavelength assignment scheme called the wavelength pre-assignment collision schedule （WPCS） is proposed for wavelength-routed networks. The WPCS pre-assigns the wavelength at the forward detection phase, and schedules the potential collision by priority. The potential collision is scheduled at the forward detection phase and the blocking of the wavelength assignment is reduced. Simulation is conducted with several other existing schemes. The numerical results show that WPCS performs better than other schemes in blocking probability under various traffic conditions.     

A Realization of Quantum Groups via Product Valued Quivers

Let C be the symmetrizable generalized Cartan matrix associated to a valued quiver \(\overset{\rightarrow}{\Gamma}\). We show that the whole quantum group associated to C can be realized from the abelian category of the representations of the product valued quiver \(\overset{\rightarrow}{\Gamma^{\pm}}\) of \(\overset{\rightarrow}{\Gamma}\) with the Kronecker quiver. This method can be used to realize the whole generalized Kac–Moody Lie algebra associated to C, as discussed in Li and Lin (submitted for publication, arXiv:math/0610448).     

Finitely Σ-CS Property of Excellent Extensions of Rings

For a right excellent extension S of a ring R, it is proved that R is right, finitely -CS if and only if S is the same. As an application of this result, a number of examples of group rings which are finitely -CS are presented. This generalizes a result of Jain, et al. [5], where it was shown that F[D] is CS when F is a field of characteristic 2. It is also proved that if R is a commutative domain with 2^–1 R and C₂ is the cyclic group of order 2, then R[C₂] is a CS-ring.2000 Mathematics Subject Classification: 16S20, 16D50The research was supported by the NSERC of Canada, grants A8775 and OGP0194196.