An efficient numerical approach, for determining the dispersioncharacteristics of dual-mode elliptical-core optical fibers

Based on vectorial formulations which combine the surface integral equation method and the finite-element method, a novel numerical approach is proposed for calculating the dispersion coefficients of dual-mode elliptical-core fibers with arbitrary refractive index profiles. By differentiating the original formulations involving the propagation constant β and the guided mode fields H_x and H_y once and twice with respect to the normalized frequency V, the new formulations for {dβ/dV, dH_x/dV, dH_y/dV} and for {d²β/dV², d² H_x/dV², d²H_y/dV² } are obtained respectively. Once {β, H_x, H_y } is solved through the eigenvalue procedure which dominates the computing time, only a few matrix manipulations are required to obtain {dβ/dV, dH_x/dV, dH_y/dV} and {d²β/dV², d²H_x/dV² , d²H_y/dV²}. Some numerical examples are examined to see the influence of different refractive index distributions with dips on the dispersions of the four nondegenerate LP ₁₁ modes for elliptical-core fibers     

A CMOS differential buffer amplifier with accurate gain andclipping control

A CMOS fully differential buffer amplifier with accurate gain and clipping control is presented. The gain is made variable by controlling the amount of the feedback around the power amplifier by means of an additional gain control loop. A new clipping technique is used to control the clipping level of the amplifier. The amplifier is realized in a 1.2 μm CMOS process with a single 5 V power supply. Measurements confirm the presented techniques     

Recent advances in theory and applications of scrambling techniquesfor lightwave transmission

This paper discusses recent advances in the theory and applications of scrambling techniques for digital lightwave transmission. It introduces the theories of sequence space and shift register generator (SRG) space which enable systematic analysis and mathematical manipulation of the behavior of sequences in general and the related SRG's. It discusses the behavior and realization of frame synchronous scrambling (FSS) and distributed sample scrambling (DSS) with emphasis on parallel sequences and the related parallel SRG's (PSRG). In addition, it describes self synchronous scrambling (SSS). Then the paper applies the theories to today's lightwave transmission systems by demonstrating practical parallel designs of FSS for SDH/SONET transmission, DSS for cell-based ATM transmission, and SSS for SDH-based ATM transmission. It finally considers how DSS can be used for scrambling of mixed isochronous and nonisochronous data in future high-speed data networks. The paper employs various new concepts and terminology, such as PSRG engine, generating vector discrimination matrix, (M,N) PSRG, sampling vector, correction vector, correction matrix, predictable scrambling concurrent sampling, and immediate correction     

Low-temperature growth of silicon-boron layer as solid diffusionsource for polysilicon contacted p+-n shallow junction

A new material, Si-B, is proposed as a solid diffusion source for fabrication of poly-Si contacted p⁺-n shallow junctions. The junction depth of the Si-B source diode has been measured and compared with that of a BF₂⁺-implanted poly-Si source diode. It was found that the Si-B source diode had a much shallower junction and was less sensitive to thermal budget than the BF₂⁺ source diode. This was attributed to the smaller surface concentration and diffusivity of boron in the silicon in Si-B source diodes. Regarding electrical characteristics of diodes with a junction depth over 500 Å, a forward ideality factor of better than 1.01 over 8 decades and a reverse-current density lower than 0.5 nA/cm² at -5 V were obtained. As the junction depth shrank to 300 Å, the ideality factor and reverse current density of diodes increased slightly to 1.05 and 1.16 nA/cm², respectively. These results demonstrated that a uniform ultrashallow p⁺-n junction can be obtained by using a thin Si-B layer as a diffusion source     

The inhibition of DMBA-induced carcinogenesis by neoxanthin in hamster buccal pouch

Neoxanthin, a major carotenoid pigment of spinach, is found in the Chloroplast membrane and has an unknown function in plants. Neoxanthin inhibited the production of superoxide anions in an artificial xanthine and xanthine oxidase system and depressed DNA synthesis in methylcholanthrene (MCA)-initiated C3H10T1/2 fibroblasts. in two-stage carcinogenesis experiments, neoxanthin at 0.2 micrograms/0.2 ml inhibited the formation of tumors that were induced sequentially by 7,12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA) in the buccal pouch of Syrian Golden hamsters. To assess the ongoing process of carcinogenesis, the activity of ornithine decarboxylase (ODC), required for cell proliferation, was analyzed. Neoxanthin inhibited the activity of ODC when animals were treated with neoxanthin one hour before the application of TPA in two-stage carcinogenesis. However, neoxanthin did not inhibit ODC activity when animals were treated with neoxanthin one hour before the application of DMBA in two-stage carcinogenesis, and there was no subsequent tumor formation. In a short-term anti-initiation experiment, neoxanthin inhibited the covalent binding of isotope-labeled DMBA to DNA by 53%. These results indicate that neoxanthin inhibits the initiation stage and the promotion stage in two-stage carcinogenesis. This suggests that neoxanthin may act as a potential chemopreventive agent.     

Nursing diagnoses and construct validity of pain, self-care deficit and impaired mobility

Construct validity of the concepts of pain, self-care deficit and impaired mobility was examined in a study of 120 medical-surgical patients. Factors derived from a factor analysis of the empirical signs and symptoms were: pain-factor and self-care deficit/impaired mobility-factor. The pain-factor clearly showed discriminant validity by differentiating between those with and without Clinical Nurse Specialist (CNS)-identified diagnosis of pain. An overlap between the defining characteristics of the diagnoses of self-care deficit and impaired mobility has been suggested in the present sample of patients. Limitations of the study and recommendations for further research are described.     

Statistical computer-aided design for microwave circuits

A useful methodology for microwave circuit design is presented. A statistical technique known as Design of Experiments is used in conjunction with computer-aided design (CAD) tools to obtain simple mathematical expressions for circuit responses. The response models can then be used to quantify response trade-offs, optimize designs, and minimize circuit variations. The use of this methodology puts the designer's intelligence back into design optimization while making “designing for circuit manufacturability” a more systematic and straightforward process. The method improves the design process, circuit performance, and manufacturability. Two design examples are presented in context to the new design methodology     

武钢“八五”技术进步的新起点

本文论述了武钢新三号高炉的建设和投产,是武钢整个“八五”技术进步的新起点,指出必须进一步完善以质量为核心的生产管理体系。     

Substrate-connected high voltage pumping circuits for low supplyvoltages

Novel high voltage pumping circuits for low supply voltages are proposed. Utilising a small pumping circuit and the new substrate-connected techniques can enhance charge transfer efficiency and eliminate the body effect at low supply voltages. Furthermore, a diode-connected transistor technique can improve the reverse charge sharing phenomenon when the output has a load current. With this technique high boosted voltages can be obtained at low supply voltages     

四川省水电厂技术改造的实践与展望

四川省电力工业局管辖的水电厂总装机容量为２６１７．５ＭＷ，针对受自然条件限制相当多的机组运行条件恶劣，早期建设的水电站辅助设备和控制系统质量差，自动化水平低等问题，省电力局加强了对水电厂的技术改造，进行了包括对渔子溪型水电机组和龚嘴水电站机组的改造增容，对龚嘴和映秀湾等电厂的综合自动化改造，以及部分水电厂的水工建筑物技术改造等工作，同时加强了技改管理工作，加快了技改工作的进行，提高了技改的质量，取