智能网SCP的两级并发模型与软件容错研究

智能网作为一种能够快速灵活地定义与提供电信新业务的体系结构，近年来受到人们的普遍重视，其中，业务控制点ＳＣＰ作为整个系统的核心，它的可靠性与全网的服务质量息息相关。本文中，我们首先指出了目前的ＳＣＰ产品在容错性能上存在的不足，然后根据ＳＣＰ的结构和运行机制提出一种两级并发模型，并基于此模型对其软件容错的途径进行了深入的探讨与研究。本文首次提出了应用软件出错情况下保证所有在线呼叫可靠处理的容错目标，并在ＳＣＰ系统级与呼叫级两个并发层次上给出了切实可行的容错策略或算法，最后，我们还对ＳＣＰ软件有效度的估算进行了进一步讨论。     

在帧中继骨干网上传送话音的技术

在帧中继网上传送话音（ＶｏＦＲ）是帧中继网上的一项增值业务。本文提出该业务的主要障碍是话音分组的时延和丢弃；接着又介绍了克服这些障碍的技术，包括话音压缩、采用回波消除器和抖动缓冲器以及优先级技术等；最后又探讨了ＶｏＦＲ的兼容性和标准化问题。     

Detection of Carbon Dioxide in Air Using Difference-Frequency Generation Based Infrared Spectrometer

Spectroscopic detection of carbon dioxide (CO₂) in ambient air was performed using a continuous-wave mid-infrared spectrometer based on difference-frequency generation in an AgGaS₂ crystal. Significant improvement in nonlinear optical frequency conversion efficiency was achieved by Gaussian beam optical design consideration. CO₂ concentration was determined from direct-absorption spectral measurement.     

非对称单脊波导裂缝阵天线分析

将Ｅｌｌｉｏｔｔ关于矩形波导缝阵理论推广运用到非对称单脊波导裂缝阵天线上，在考虑了裂缝外部互耦影响的情况下，给出相应的两个设计方程，同时给出８单元谐振裂缝线阵的具体计算和设计方法。加工样品的近场和远场测试结果证明了本文理论和设计方法是正确有效的。     

Fuzzy stack filters-their definitions, fundamental properties, andapplication in image processing

A new fuzzy filter, called fuzzy stack filter (FSF), is proposed to extend the filtering capability of conventional stack filter (SF), which is based on the positive Boolean function (PBF) as its window operator. We fuzzify the onset and off-set of a given PBF to obtain two types of fuzzy PBFs. Then, we adopt the architecture of threshold decomposition to develop this new fuzzy filter with a fuzzy PBF as its window operator. Each fuzzy PBF is associated with a set of control parameters. Therefore, the original PBF can be estimated from above and below by two fuzzy PBFs with appropriate control parameters. Furthermore, we can apply the fuzzy modifiers to modify the fuzzy PBFs such that the PBFs can be completely estimated by the fuzzy PBFs. Hence, the stack filter is a special case of fuzzy stack filter. Since some control parameters are added in this new filter, the neural learning algorithms can be easily developed under the flexibility of the given control parameters. We first propose the fuzzy (m,n) rank-order filter to test our proposed learning algorithm. In this simple learning algorithm, we can remove the noise-corrupted images very well in contrast to the filtering behavior of rank-order filters. We believe that the results presented will lead to more fruitful research on more advanced and powerful learning algorithms dedicated to the appropriate applications.     

Optimal image sampling schedule: a new effective way to reduce dynamic image storage space and functional image processing time

An optimal image sampling schedule for tracer dynamic studies with positron emission tomography (PET) is proposed. This schedule incorporates the characteristics of PET measurement and uses a new cost function and the D-optimal criterion. A detailed case study of the estimation of the local cerebral metabolic rate of glucose (LCMRGLc) using the tracer fluorodeoxyglucose (FDG) and the four-parameter FDG model is presented. As the sampling schedule designed requires only four dynamic images, the storage space and data processing time are greatly reduced, while the precision of the parameter estimates is almost the same as that achieved with a commonly used schedule. The effects of intersubject and intrasubject parameter variations on parameter estimation with the use of this optimal sampling schedule are investigated by computer simulation. The simulation results show that the estimation of parameters is sufficiently robust with respect to these intersubject and intrasubject variations. The optimal sampling schedule is quite suitable therefore for PET regional parameter estimation, as well as for image-wide parameter estimation, for different subjects.     

The available bit rate service for data in ATM networks

The authors describe the purpose of the available bit rate (ABR) service in the context of other ATM services and review the agreements on the traffic control mechanism. They describe the recent progress towards standardization of the new service. The general nature of the ABR service is described in comparison with constant bit rate (CBR) and variable bit rate (VBR) services     

Finite-difference time-domain algorithm for solving Maxwell'sequations in rotationally symmetric geometries

In this paper, an efficient finite-difference time-domain algorithm (FDTD) is presented for solving Maxwell's equations with rotationally symmetric geometries. The azimuthal symmetry enables us to employ a two-dimensional (2-D) difference lattice by projecting the three-dimensional (3-D) Yee-cell in cylindrical coordinates (r, φ, z) onto the r-z plane. Extensive numerical results have been derived for various cavity structures and these results have been compared with those available in the literature. Excellent agreement has been observed for all of the cases investigated     

A novel soft-switched PWM inverter for AC motor drives

A novel soft-switched inverter topology is derived from the passively clamped quasi-resonant link (PCQRL) circuit. By introducing magnetic coupling between the two resonant inductors, the number of auxiliary switches can be reduced from two to one, and only a single magnetic core is required for the resonant DC link. An analysis of this novel PCQRL topology with coupled inductors is presented to reveal the various soft-switching characteristics. In comparison with the conventional passively clamped, continuously resonant DC link inverter, this soft-switched inverter can reduce voltage stresses from more than 2 per unit (pu) to 1.1-1.3 pu. It can also provide soft-switched pulse-width modulated (PWM) operation. Simulations and experiments are performed to backup the analysis     

Integrated VP-Based Control Strategies for ATM Survivable Networks

ＩｎｔｅｇｒａｔｅｄＶＰ－ＢａｓｅｄＣｏｎｔｒｏｌＳｔｒａｔｅｇｉｅｓｆｏｒＡＴＭＳｕｒｖｉｖａｂｌｅＮｅｔｗｏｒｋｓ￥ＣｈｅｎＳｈａｎｚｈｉ；ＣｈｅｎｇＳｈｉｄｕａｎ；ａｎｄＣｈｅｎＪｕｎｌｉａｎｇ（ＳｔａｔｅＫｅｙＬａｂｏｒａｔｏｒｙｏｆＳｗｉｔ...