Approximately isometric lifting in quasidiagonal extensions

Let 0 → I → A → A/I → 0 be a short exact sequence of C*-algebras with A unital. Suppose that the extension 0 → I → A → A/I → 0 is quasidiagonal, then it is shown that any positive element (projection, partial isometry, unitary element, respectively) in A/I has a lifting with the same form which commutes with some quasicentral approximate unit of I consisting of projections. Furthermore, it is shown that for any given positive number ε, two positive elements (projections, partial isometries, unitary elements, respectively) in A/I, and a positive element (projection, partial isometry, unitary element, respectively) a which is a lifting of , there is a positive element (projection, partial isometry, unitary element, respectively) b in A which is a lifting of such that ∥a−b∥ < . As an application, it is shown that for any positive numbers ε and in U(A/I) ₀ , there exists u in U(A)₀ which is a lifting of such that cel(u) < cel. This work was supported by National Natural Science Foundation of China (Grant No. 10771161)     

基于LM神经网络的起重机械本质安全评价方法

由于起重机械特殊的结构形式和运动形式,导致起重机械事故频发,为提高起重机械的本质安全,提出了一套起重机械本质安全评估体系,从本质安全的4个方面分3个层次对起重机械进行评估;为了改善在评估过程中,人为主观因素对起重机械状态评分的影响,引入LM神经网络对起重机械评价体系     

Commutant Lifting for Optimal Control of Time-varying Systems

This paper uses the commutant lifting theorem for representations of the nest algebra to deal with the optimal control of infinite dimensional linear timevarying systems.We solve the model matching pro...     

A high-efficiency aerothermoelastic analysis method

In this paper,a high-efficiency aerothermoelastic analysis method based on unified hypersonic lifting surface theory is established.The method adopts a two-way coupling form that couples the structure,aerodynamic force,and aerodynamic thermo and heat conduction.The aerodynamic force is first calculated based on unified hypersonic lifting surface theory,and then the Eckert reference temperature method is used to solve the temperature field,where the transient heat conduction is solved using Fourier’s law,and the modal method is used for the aeroelastic correction.Finally,flutter is analyzed based on the p-k method.The aerothermoelastic behavior of a typical hypersonic low-aspect ratio wing is then analyzed,and the results indicate the following:(1)the combined effects of the aerodynamic load and thermal load both deform the wing,which would increase if the flexibility,size,and flight time of the hypersonic aircraft increase;(2)the effect of heat accumulation should be noted,and therefore,the trajectory parameters should be considered in the design of hypersonic flight vehicles to avoid hazardous conditions,such as flutter.     

On the facets of the mixed–integer knapsack polyhedron

We study the mixed–integer knapsack polyhedron, that is, the convex hull of the mixed–integer set defined by an arbitrary linear inequality and the bounds on the variables. We describe facet–defining inequalities of this polyhedron that can be obtained through sequential lifting of inequalities containing a single integer variable. These inequalities strengthen and/or generalize known inequalities for several special cases. We report computational results on using the inequalities as cutting planes for mixed–integer programming.Supported, in part, by NSF grants DMII–0070127 and DMII–0218265.Mathematics Subject Classification (2000): 90C10, 90C11, 90C57     

I半π正则环

Let R be a ring and I an ideal of R.A ring R is called I-semi-π-regular if R/I isπ-regular and idempotents of R can be strongly lifted modulo I.Charac- terizations of I-semi-π-regular rings are given and relations between semi-π-regular rings and semiregular rings are explored.     

Valid inequalities for the multi-dimensional multiple-choice 0–1 knapsack problem

This paper presents a study of the polytope defined by the minimizing form of the binary knapsack inequality, which is a greater-than-or-equal-to constraint, augmented by disjoint generalized upper bound constraints. A set of valid inequalities, called $\alpha$-cover inequalities, is characterized and dominance relationships among them are established. Both sequential and sequence-independent lifting procedures are presented to tighten an $\alpha$-cover inequality that is not facet defining. Computational results aimed at evaluating the strength of the non-dominated, sequentially, and sequence-independent lifted $\alpha$-cover inequalities are provided.