相干光正交频分复用传输系统中的 无导频相位纠偏方法

提出了一种适用于16-QAM的新型相位纠偏方法,克服了基于M次方算法的传统相位纠错方法不适用于高阶正交振幅调制的缺点.该方法结合正交频分复用调制方式,无需导频即可完成相位盲估计,且计算量较少.本文基于112 Gb/s 1 040 km的相干光正交频分复用传输系统进行了算法验证,并与传统的4次方纠偏方法进行了比较,实验证明该算法适用于正交频分复用和16-QAM调制平台,相位纠偏结果显著优于基于导频的4次方算法.     

Necessary versus equal players in axiomatic studies

This note introduces three variants of existing axioms in which equal players are replaced by necessary players. We highlight that necessary players can replace equal players in many well-known axiomatic characterizations, but not in all. In addition, we provide new characterizations of the Shapley value, the class of positively weighted Shapley values, the Solidarity value and the Equal Division value. This sheds a new light on the real role of equal treatment of equals in the axiomatic literature.     

Gelfand–Mazur Theorems in normed algebras: A survey

The Gelfand–Mazur Theorem, a very basic theorem in the theory of Banach algebras states that: (Real version) Every real normed division algebra is isomorphic to the algebra of all real numbers $\mathbb{R}$, the complex numbers $\mathbb{C}$ or the quaternions $\mathbb{H}$; (Complex version) Every complex normed division algebra is isometrically isomorphic to $\mathbb{C}$. This theorem has undergone a large number of generalizations. We present a survey of these generalizations and also discuss some closely related unsettled issues.     

Conservative finite difference schemes for the generalized Zakharov–Kuznetsov equations

This paper is concerned with the construction of conservative finite difference schemes by means of discrete variational method for the generalized Zakharov–Kuznetsov equations and the numerical solvability of the two-dimensional nonlinear wave equations. A finite difference scheme is proposed such that mass and energy conservation laws associated with the generalized Zakharov–Kuznetsov equations hold. Our arguments are based on the procedure that D. Furihata has recently developed for real-valued nonlinear partial differential equations. Numerical results are given to confirm the accuracy as well as validity of the numerical solutions and then exhibit remarkable nonlinear phenomena of the interaction and behavior of pulse wave solutions.     

Polarization Insensitive Ion-Exchanged Arrayed-Waveguide Grating Multiplexers in Glass

Wavelength multiplexers based on the arrayed-waveguide grating (AWG) principle are fabricated with ion-exchanged waveguides in glass for 1550 nm. The insertion loss is 6 and 4 dB with a cross talk of 15 and 20 dB for 8-channel 50 GHz and 4-channel 100 GHz devices, respectively. The AWGs are almost polarization insensitive because the refractive index profile of the waveguides is nearly concentric and the waveguides are diffused into stress-free glass substrates. The transverse electric transverse magnetic (TETM) shift of the wavelength response is only 0.02 nm (2.5GHz) for an 8-channel 50 GHz AWG. The temperature sensitivity is 1.4 GHz C.     

Performance and comparison of fiber vibration sensing using SAC-OCDMA with direct decoding techniques

Intensity modulated fiber vibrations sensing using Khazani Syed (KS) and Modified Quadratic Congruence Code (MQC) code for quasi distributed vibration measurement have been evaluated. The systems employed Spectral Direct (SD) Decoding for Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA). SAC-OCDMA is adopted because of its enormous impact in dealing with Multiple Access Interference (MAI). The setup was carried out for three sensor points in three consecutive measurements. The performance of the sensing system with the KS and MQC codes were compared at the same weight and number of code sequence. It was observed that the applied vibration frequencies were obtained at the receivers and the signal employing MQC are received at slightly better power than KS code. However, KS code setup employed less number of components and therefore, reduce the cost and complexity of achieving quasi-distributed vibration sensing.     

基于多核点共享树的多源光组播路由方法

通过网络编码方法优化多核点选择和组播信息传输,本文提出一种基于多核点共享树和网络编码的光组播路由构造和波长分配方法、减少波长资源消耗和提高网络的负载平衡性能.首先,删除产生源点迂回回路的网络编码备选核点集合,采用启发式矩阵运算方法确定多源共享树的网络编码核点,实现多源共享树以最少的核点覆盖最多的源节点;然后,为减少波长信道消耗数目,在确定的核点到目的节点间加入网络编码方法传输信息;最后,讨论了多核点共享树的波长分配方法和目的节点成功解码的边分离路径方法.仿真结果表明:与单核共享树、基于网络编码的单核共享树相比,基于网络编码的多核点共享树组播路由方法需求最少的波长数目和获得最好的网络负载平衡性能.     

Kinetic treatment of unsegmented flow systems : Part 2. Detailed Treatment of Flow-Injection Systems with Gradient Chamber

A kinetic model is utilized for a detailed mathematical treatment and experimental evaluation of single-channel and dual-channel flow injection systems that include a gradient chamber. The kinetic model includes three distinct stages in the process, namely clearing reactant from the gradient chamber by first portions of sample, continued entry of sample into the gradient chamber, and decrease of determinant concentration in the gradient chamber via dilution and reaction with reagent. Equations predict entirely different behavioral patterns for different conditions and these predictions are verified experimentally for a wide range of conditions. The data show that the variable-time kinetic model is superior to the titration models previously utilized to describe these flow systems. The principal limitation of the kinetic equations involves an assumption of plug flow that is not completely valid. The extent of deviations from ideal behavior depend on conditions, but are negligible at low concentrations (0–50 mmol l^-1) and can be 10% or larger at higher concentrations (100 mmol l^-1). While equations are not exact, they are useful in predicting performance characteristics for a variety of conditions and experimental approaches.     

Sensitized multiphoton dissociation of UF6 IN SF6-UF6 mixtures by a tea CO2 laser

UF₆ undergoes decomposition in the presence of SF₆ when mixtures of both are irradiated with a TEA CO₂ laser. The mechanism for UF₆ decomposition may involve vibrational energy transfer from excited SF₆ and laser absorption from the same laser pulse by excited UF₆ in its vibrational quasi-continuum     

Magnetostriction and the magnetic phases of single crystal terbium-50% holmium

The c-axis magnetostriction, λ_c, has been measured in terbium-50% holmium in fields up to 2 T between the Néel and Curie temperatures. The magnitude and temperature dependence of λ_c are similar to those previously reported for dysprosium. Detailed strain measurements between the critical field, H_c, which destroys the antiferromagnetic spiral spin structure and the field induced ferromagnetic phase show that the extent of an intermediate fan phase is more limited than previous theoretical analyses have predicted. The difference between the experimental data and strains calculated from theory can be explained only in part by the influence of magnetostry calline anisotropy.