Optical DQPSK Receiver With Enhanced Dispersion Tolerance

We propose and analyze a novel differential quadrature phase-shift-keying (DQPSK) receiver architecture based on optical frequency discriminator filtering and direct detection. Our simulations show that such a receiver provides significantly enhanced tolerance to chromatic dispersion compared with the conventional delay-interferometer-based receiver. Preliminary measurement results demonstrate the novel DQPSK demodulator concept at 20 Gb/s.     

台达变频器在纺织织带盘带机上的应用

盘带机是纺织织带成品分卷设备，需要使用到收放卷控制。本文基于台达变频器在盘带机上的应用案例，论述盘带机自动化系统设计调试过程以及遇到的问题分析。     

Geotechnical properties of the soft soil in Guangzhou College City

The paper describes some geotechnical properties of the soft soils in Guangzhou College City, China, which are difficult to both sample and test. Laboratory and in situ tests were carried out to assess the physical and mechanical indices of the soils. The data were statistically analyzed and linear regression undertaken such that equations could be developed by which the geotechnical properties of the soft soils can be predicted. The statistical validity of the degree of correlation confirmed that using these equations, the mechanical indices can be estimated from physical indices determined by routine testing.      

Miniaturized Hexagonal Stepped-Impedance Resonators and Their Applications to Filters

Miniaturized hexagonal stepped-impedance resonators and their applications to bandpass filters are presented. Based on the odd- and even-mode equivalent circuits, the resonance characteristics of these resonators are investigated. A series of circuit configurations, including the third-order Chebyshev, trisection, and fifth-order cascaded trisection filters, are constructed by the proposed resonators. These filters are very compact and have good stopband responses. Measured results validate the analysis and theoretical prediction with good agreement.     

秦汉京都的道路交通建设与管理

秦汉时期形成了以京都为中心的道路交通网.京都道路的类型、功能各异,管理严格,体现了中央集权的政治特点.     

Synthesis of nonsharp distillation sequences via genetic programming

This paper addresses the application of Genetic Programming (GP) to the synthesis of multicomponent product nonsharp distillation sequences. Combined with the domain knowledge of chemical engineering, some evolutionary factors are improved, and a set of special encoding method and solving strategy is proposed to deal with this kind of problem. The system structural variable is optimized by GP and the continuous variable is optimized by the simulated annealing algorithm simultaneously. Because GP has an automatic searching function, the optimal solution can be found including distillation, splitting, blending and bypassing operations automatically without any superstructures of nonsharp distillation sequences. Three illustrative examples are presented to demonstrate the effective computational strategies.     

Application of ultrasonic waves in activation of microcrystalline cellulose

In this work, microcrystalline cellulose (MCC) was activated with ultrasonic waves. The influences of ultrasonic treatment on the changes of supramolecular structures and morphology structure were studied by WAXS and SEM. The accessibility of the MCC was characterized by water retention value (WRV) and specific surficial area. The influence of ultrasonic treatment on the reactivity of MCC was investigated through the reaction of MCC being oxidized into 2,3‐diadehyde cellulose (DAC) by periodate sodium. The mechanism of the reactivity change of ultrasonically treated MCC was examined. The results showed that the degree of crystallinity of MCC decreased and the degree of polymerization showed little change after treatment with ultrasonic waves. The morphologial variation of the treated MCC was significant when compared with the untreated MCC, which contribute to the improvement of accessibility. The aldehyde content of DAC prepared from ultrasonically treated MCC was improved from 64.19 to 85.00%, indicating that the regioselective oxidation reactivity of MCC was significantly improved. The aldehyde content was found to first increase with time of ultrasonic treatment to a point, and then decrease as time progressed. In addition, the aldehyde content was found to increase with an increase in ultrasonic power. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and aqueous solution behaviors of sodium sulfonate‐terminated dendritic poly(ester‐amine)

Sodium sulfonate‐terminated dendritic poly(ester‐amine) (SPEA) was synthesized by sulfonation of acrylic double bond‐terminated dendritic poly(ester‐amine) (APEA) with sodium hydrogen sulfite (NaHSO₃) in mixture of diglycol and 2‐butanone under normal pressure. The structure of SPEA was characterized by IR, ¹H‐NMR, and elemental analysis. SPEA was water‐soluble. 1.0–40.0% (mass) SPEA aqueous solutions appeared as dilatant fluid. When pH value varied from 1.5 to 12.0, the viscosity of 1–5% (mass) SPEA aqueous solutions changed very small, and the electric conductivity almost kept stable within pH 3.0–10.0. The relationship between the viscosity and the concentration of SPEA water solutions was similar to that of NaCl water solutions. The surface tension of SPEA water solutions was lower than that of polyethylene glycol 2000 water solutions with the same concentration. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008