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排序方式: 共有367条查询结果,搜索用时 31 毫秒
1.
混凝土中钙矾石作用的二重性及其发生条件 总被引:1,自引:0,他引:1
钙矾石被广泛用来提高混凝土或胶凝材料的早期强度 ,或被用来生产收缩补偿混凝土 ,而延迟钙矾石的形成却引起混凝土的胀裂性破坏 ,这就形成了钙矾石作用的矛盾的二重性。探讨了混凝土中钙矾石的形成机理、结晶构造、形成条件、稳定性及延迟钙矾石的成因、危害 ,旨在揭示钙矾石作用的二重性 ,力求找出抑制延迟钙矾石膨胀的途径 ,更好地发挥钙矾石的优越性能 相似文献
2.
Kazuhiro Umetani 《IEEJ Transactions on Electrical and Electronic Engineering》2016,11(4):521-530
This paper proposes a novel method for deriving dual converters, namely deriving current‐source converters from voltage‐source counterparts, and vice versa. The conventional derivation method is based on the transformation of circuit topology, in which series connections are converted into parallel connections, and vice versa. However, this method cannot be directly applied to nonplanar circuits because they do not allow perfect topological transformation, although many of them are known to have duals. Lagrangian dynamics does not depend on the topological relation to transform a system into another equivalent system; therefore, it possibly avoids problems related to topological transformation and may provide a universal and systematic method that can be consistently applied to nonplanar circuits. This paper discusses the derivation of duals using Lagrangian dynamics. Along with the theory, this paper presents two examples of Lagrangian derivation of duals. One derives a dual of a planar circuit, to which the topological transformation is applicable. The other derives two duals of a nonplanar circuit. Consequently, these examples suggest that the proposed method is a prospective candidate for universal and systematic derivation of duals. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
3.
相位波带片型时间透镜研究 总被引:1,自引:0,他引:1
基于Opti-System软件,对相位波带片型时间透镜进行了深入研究。明确了中心波长对相位波带片型时间透镜焦距色散补偿量的影响机理,建立了中心波长、色散补偿量与输出光脉冲消光比及脉冲宽度间的关系。研究结果表明,相位波带片型时间透镜的焦距色散补偿量,在1 310~1 550 nm波长范围与光信号中心波长呈近似线性关系。通过线性拟合,得出焦距色散补偿量与中心波长的线性关系公式。对于不同波长的输入光波,可通过公式确定最佳焦距色散补偿量,实现最窄脉宽和最优消光比的光脉冲输出。研究结果可为优化相位波带片型时间透镜设计提供理论指导,进而拓宽相位波带片型时间透镜的应用范围。 相似文献
4.
提出了最大可靠性网络流中断模型。此模型是在给定的网络图中,通过在边上设置监测点来阻止给定两个顶点之间的网络流量,同时考虑所设置监测点失效的可能,在给定的资源限制下,最大化中断网络流的可能性,即给定起点和终点的网络图,在资源有限的情况下,选择一些边设置监测点使得从起点到终点的所有路都包含尽可能多的已被设置中断点的边。在给定图中,两点之间的路的条数是图的规模的指数次幂,为此将此模型转化为双层整数规划模型,鉴于双层整数规划模型在一般情况下是不可解的,通过探讨下层整数规划问题与其线性规划松弛之间的关系以及线性规划对偶理论来解此双层整数规划模型。本文不仅将该模型约束的个数从图的规模的指数次幂降到一次幂,同时也提供了一种解双层整数规划问题的方法。 相似文献
5.
Federico Najson 《International journal of control》2016,89(4):770-782
The present communication is concerned with uniform exponential stability, under arbitrary switching, in discrete-time switched positive linear systems. Lagrange duality is used in order to obtain a new characterisation for uniform exponential stability which is in terms of sets of inequalities involving each of the matrices that represent the modes of the system. These sets of inequalities are shown to generalise the classical linear Lyapunov inequality that characterises, in positive matrices, the property of being Schur. Each solution to these sets of inequalities is shown to provide a representation, in terms of a number of linear functionals, for a common Lyapunov function for the switched positive linear system. A result is further presented which conveys to, a conservative upper bound on the minimum required number of linear functionals (in the above mentioned representation), and also to a method for computing them. Our proof for the aforementioned characterisation is based on another (equivalent) characterisation, in terms of the solvability of a dynamic programming equation associated to the switched positive linear system, which is also reported in the paper. In particular, it is shown that the associated dynamic programming equation has at most one solution. And this solution is shown to be convex, monotonic, positively homogeneous, and it yields a common Lyapunov function for the switched positive linear system. 相似文献
6.
Savin Treanţă 《Computers & Mathematics with Applications》2018,75(2):547-560
This paper, using a non-standard Legendrian duality, investigates the Hamiltonian dynamics and formulates a Hamilton–Jacobi type divergence PDE governed by higher-order Lagrangians. 相似文献
7.
《国际计算机数学杂志》2012,89(8):1345-1354
In this paper, we deal with the multiple-objective optimization problems, considering an improved definition of generalized type I univex function. Some optimality conditions as well as some duality relations are established. 相似文献
8.
T. C. E. CHENG 《工程优选》2013,45(2):127-130
This paper considers the problem of determining the optimal constant flow allowance for the CON due-date assignment method. A linear programming formulation of the problem is proposed and the optimal due-date is obtained by solving the LP dual problem. 相似文献
9.
This paper presents a novel spectrum sharing design aiming at optimising the performance of a Multiuser Orthogonal Frequency-Division Multiplexing(MU-OFDM) Cognitive Radio Network(CRN) that consists of multiple secondary Transmitter-Receiver(Tx-Rx)pairs.For most MU-OFDM systems,the Exclusive Subchannel Assignment(ESA) is an efficient resource allocation method.Nonetheless,it is inappropriate for the network considered in this paper,because subchannels sharing among secondary Tx-Rx pairs can further improve the system performance.We investigate the Weighted Sum Rate(WSR) maximization problem under the Shared Subchannel Assignment(SSA),where each subchannel is shared by multiple secondary Tx-Rx pairs.With Lagrangian duality technique,we decompose the original resource allocation problem into several sub-problems on each subchannel and propose a duality-based subchannel sharing approach.For practical realisation in the cognitive systems without central control entity,a distributed duality-based WSR maximization scheme is presented.Simulation results manifest that the proposed scheme achieves significantly better performance than ESA duality scheme. 相似文献
10.