An iterative ADI-FDTD with reduced splitting error

We present a new iterative alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method. By recognizing the ADI-FDTD method as a special case of a more general iterative approach to solve the Crank-Nicolson (CN) FDTD scheme, the splitting error in ADI-FDTD can be reduced systematically. Numerical examples are used to illustrate the improved accuracy of this method.     

Widely tunable bottom-emitting vertical-cavity SOAs

We present bottom-emitting tunable vertical-cavity semiconductor optical amplifiers (VCSOAs) with an effective wavelength tuning range of >20 nm. These devices utilize a high reflectivity micromechanically tunable Bragg mirror as the back reflector. Compared with our first generation tunable VCSOAs, the bottom-emitting devices exhibit a two-fold increase in the effective tuning range as well as a five-fold reduction in the required tuning voltage.     

An experimental study of carrier heating on channel noise in deep-submicrometer NMOSFETs via body bias

In this paper, RF noise in 0.18-mum NMOSFETs concerning the contribution of carrier heating and hot carrier effect is characterized and analyzed in detail via a novel approach that modulates the channel carrier heating and number of hot carriers using body bias. We confirm qualitatively a negligible role of hot carrier effect on the channel noise in deep-submicrometer MOSFETs. For a device under reverse body bias (V_b), even though the increase in hot carrier population is clearly characterized by dc measurements, the device high-frequency noise is found to be irrelevant to the increase in the channel hot carriers. Experimental results show that the high-frequency noise is slightly reduced with the increase in |V_b|, and can be qualitatively explained by secondary effects such as the suppression of nonequilibrium channel noise and substrate induced noise. The reduction of NF_min and R_n with the increase in |V_b| may provide a possible methodology to finely adjust the device high-frequency noise performance for circuit design     

ADS7822及其在CO气体浓度监测仪中的应用

在介绍TI公司的12位串行、高速、微功耗A/D转换器ADS7822工作原理的基础上,以ADS7822在CO气体浓度监测仪的前向通道设计中的应用为例,讨论了它与AT2051单片机的硬件接口问题,给出了利用ADS7822进行A/D转换的51汇编语言程序,并做了详细注释.串行、微功耗及小型封装使ADS7822非常适合电池供电的智能便携式仪器采用.     

Quantum diffusion

Basic ideas and results which characterize quantum diffusion of defects in quantum crystals like solid helium as a new phenomenon are presented. Quantum effects in such media lead to a delocalization of point defects (vacancies, impurities etc.) and they turn into quasiparticles of a new type—defectons, which are characterized not by their position in the crystal lattice but by their quasimomentum and dispersion law. Defecton-defecton and defecton-phonon scattering are considered and an interpolation formula for the diffusion coefficient valid in all interesting temperature and concentration regions is presented. A comparison with the experimental data is made. Some alternative points of view are discussed in detail and the inconsistency of the Kisvarsanyi-Sullivan theory is shown.     

Skew-Hermitian Triangular Splitting Iteration Methods for Non-Hermitian Positive Definite Linear Systems of Strong Skew-Hermitian Parts

By further generalizing the skew-symmetric triangular splitting iteration method studied by Krukier, Chikina and Belokon (Applied Numerical Mathematics, 41 (2002), pp. 89–105), in this paper, we present a new iteration scheme, called the modified skew-Hermitian triangular splitting iteration method, for solving the strongly non-Hermitian systems of linear equations with positive definite coefficient matrices. We discuss the convergence property and the optimal parameters of this new method in depth. Moreover, when it is applied to precondition the Krylov subspace methods like GMRES, the preconditioning property of the modified skew-Hermitian triangular splitting iteration is analyzed in detail. Numerical results show that, as both solver and preconditioner, the modified skew-Hermitian triangular splitting iteration method is very effective for solving large sparse positive definite systems of linear equations of strong skew-Hermitian parts.     

Broad-band MMICs based on modified loss-compensation method using 0.35-/spl mu/m SiGe BiCMOS technology

Using the concept of loss compensation, novel broad-band monolithic microwave integrated circuits (MMICs), including an amplifier and an analog multiplier/mixer, with LC ladder matching networks in a commercial 0.35-mum SiGe BiCMOS technology are demonstrated for the first time. An HBT two-stage cascade single-stage distributed amplifier (2-CSSDA) using the modified loss-compensation technique is presented. It demonstrates a small-signal gain of better than 15 dB from dc to 28 GHz (gain-bandwidth product=157 GHz) with a low power consumption of 48 mW and a miniature chip size of 0.63 mm² including testing pads. The gain-bandwidth product of the modified loss-compensated CSSDA is improved approximately 68% compared with the conventional attenuation-compensation technique. The wide-band amplifier achieves a high gain-bandwidth product with the lowest power consumption and smallest chip size. The broad-band mixer designed using a Gilbert cell with the modified loss-compensation technique achieves a measured power conversion gain of 19 dB with a 3-dB bandwidth from 0.1 to 23 GHz, which is the highest gain-bandwidth product of operation among previously reported MMIC mixers. As an analog multiplier, the measured sensitivity is better than 3000 V/W from 0.1 to 25 GHz, and the measured low-frequency noise floor and corner frequency can be estimated to be 20 nV/sqrt(Hz) and 1.2 kHz, respectively. The mixer performance represents state-of-the-art result of the MMIC broad-band mixers using commercial silicon-based technologies     

On the stability of Riemannian manifold with parallel spinors

Inspired by the recent work [HHM03], we prove two stability results for compact Riemannian manifolds with nonzero parallel spinors. Our first result says that Ricci flat metrics which also admit nonzero parallel spinors are stable (in the direction of changes in conformal structures) as the critical points of the total scalar curvature functional. Our second result, which is a local version of the first one, shows that any metric of positive scalar curvature cannot lie too close to a metric with nonzero parallel spinor. We also prove a rigidity result for special holonomy metrics. In the case of SU(m) holonomy, the rigidity result implies that scalar flat deformations of Calabi-Yau metric must be Calabi-Yau. Finally we explore the connection with a positive mass theorem of [D03], which presents another approach to proving these stability and rigidity results. Dedicated to Jeff Cheeger for his sixtieth birthday     

Representations of Positive Projections II

In this paper we obtain a number of Maharam-type slice integral representations, with respect to scalar measures, for positive projections in Dedekind complete vector lattices and f-algebras. AMS Classification: 47B65, 46A40, 06F25     

APT（STLRI）—1.78型单模光纤（缆）连接器简介

利用引进的制造技术和设备,制作出了 APT(STLRI)—1.78型系列化光纤连接器。