有线数字电视射频信号调制识别研究

从有线数字电视射频信号特征参数提取着手,建立了一套识别16QAM和64QAM射频信号调制方式的数学算法。试验仿真和实际信号验证表明,该算法计算量小,识别率高,易于实现。本项研究为广播电视安全播出和数字电视终端整合提供有益的技术实践。     

有线电视多路数字微波联网传输技术

本文介绍了有线电视多路数字微波传输技术,分析了各种技术的特点;以及对大连长海县多路电视微波联网工程案例进行介绍。     

16QAM基带成形滤波器的FPGA实现

根据16QAM的调制原理,提出一种采用现场可编程门阵列(FPGA)实现16QAM成形的FIR数字滤波器硬件电路的方案。该方案基于分布式算法的思想,利用FPGA丰富的查找表资源,从时域上对基带信号直接进行成形。因为所采用的成形方法运算量小、精度高,所以适用于实时系统。     

一种改进的差分空时协同分集方案及误码性能分析

提出了一种分布式差分空时分集方案，通过对差分编码方式的改进，可使用多种星座形状来进行调制。在采用了QAM星座调制时，比传统的PSK调制具有更好的性能，可以改善无线网络中的能量效率。在不考虑协同节点间误码的情况下，分析和推导了平坦衰落瑞利信道下该方案的SER性能上限的表达式。仿真结果表明采用QAM调制下的DSTBC性能优于PSK调制下的DSTBC。同时在慢衰落的条件下，仿真结果和理论分析的结果吻合较好，说明了方案的有效性。     

Erratum: On the Contractions of Vectorial Lattice Representations

An isometric sublattice on a six-dimensional vector space lattice is constructed having a congruence relation such that the factor lattice does not admit any representation via contraction.     

Complete Axiomatizations for Quantum Actions

We present two equivalent axiomatizations for a logic of quantum actions: one in terms of quantum transition systems, and the other in terms of quantum dynamic algebras. The main contribution of the paper is conceptual, offering a new view of quantum structures in terms of their underlying logical dynamics. We also prove Representation Theorems, showing these axiomatizations to be complete with respect to the natural Hilbert-space semantics. The advantages of this setting are many: (1) it provides a clear and intuitive dynamic-operational meaning to key postulates (e.g. Orthomodularity, Covering Law); (2) it reduces the complexity of the Solèr–Mayet axiomatization by replacing some of their key higher-order concepts (e.g. “automorphisms of the ortholattice”) by first-order objects (“actions”) in our structure; (3) it provides a link between traditional quantum logic and the needs of quantum computation. PACS: 02.10.-v Logic; set theory and algebra; 03.65.-w Quantum mechanics; 03.65.Fd Algebraic methods; 03.67.-a Quantum information.     

Morita Contexts and their Lattices of Relations

We study the interaction between the lattices of relations of members of a general Morita context. The pairs of reversing-order maps are defined, which determine the dualities between the lattices of ‘closed’ relations. Under rather weak conditions, these dualities can be composed obtaining the projectivities defined by simple maps. PACS: 02.10.De,02.10.Hh.     

Huang diffuse scattering from interstitials in an hcp lattice

Using the continuum theory of linear elasticity, the Huang diffuse scattering from interstitials in an hcp lattice has been calculated to distinguish between the possible interstitial configurations. The symmetry of the lattice permits four such configurations. In each case, the Huang diffuse scattering is averaged over all possible equivalent orientations (assumed to be equally populated) of the defect configuration. The limitations of Huang diffuse scattering in discriminating between defect configurations having the same long-range symmetry are discussed, considering the specia I cases of Mg and Zn.     

Lattice dynamics of molybdenum and tungsten

Summary The lattice dynamics of molybdenum and tungsten has been re-examined within the framework of the transition metal model potential by incorporating the local-field correction to the dynamical matrix for phonon dispersion relation. It is observed that the local-field correction can be represented by an attractive short-range potential which tends to cancel or ?screen? the Born-Mayer repulsion. The numerical calculations for molybdenum and tungsten show that the local-field correction plays a significant role and leads to a better agreement between the theoretically computed phonon dispersion curves and the experimental data.     

An Algebraic Version of the Cantor-Bernstein-Schröder Theorem

The Cantor-Bernstein-Schröder theorem of the set theory was generalized by Sikorski and Tarski to -complete boolean algebras, and recently by several authors to other algebraic structures. In this paper we expose an abstract version which is applicable to algebras with an underlying lattice structure and such that the central elements of this lattice determine a direct decomposition of the algebra. Necessary and sufficient conditions for the validity of the Cantor-Bernstein-Schröder theorem for these algebras are given. These results are applied to obtain versions of the Cantor-Bernstein-Schröder theorem for -complete orthomodular lattices, Stone algebras, BL-algebras, MV-algebras, pseudo MV-algebras, ukasiewicz and Post algebras of order n.