中心局搬迁中SDH传输网的割接组网方案

本文介绍了某中心局搬迁中SDH传输网的割接组网方案.     

Energy enhancement of dispersion-managed solitons in optical fibertransmission systems with lumped amplifiers

We simulated dispersion-managed soliton propagation in optical fiber transmission systems with lumped amplifiers and loss. The energy enhancement of dispersion-managed solitons can be more or less than in the lossless case, depending delicately on the amplifiers arrangement. In all cases, there is a maximum enhancement factor beyond which the dispersion-managed soliton no longer exists and which also depends delicately on the arrangement     

指针技术在SDH中的应用

SDH（Synchronous Digital Hierarchy）设备是一种在通信传输领域得到广泛应用的设备。在SDH技术中,指针技术是一项重要的部分。丈中详细介绍了其基础知识以及这一技术在SDH中的具体应用。     

Design and optimization of an integrated MEMS gas chamber with high transmissivity

Non-Dispersive InfraRed (NDIR) gas sensor is widely used for gas detection in collieries and the gas chemical industry, etc. The performance of the NDIR gas sensor depends on the volume, optical length and transmittance of the gas chamber. However, the existing gas sensor products have problems of large volume, high cost and incapable of integration, which need to develop towards the miniaturized sensor. This paper first presents the theoretical background of the NDIR gas sensor and the novel structure of a fully integrated infrared gas sensor and its micro-machined gas chamber structure. Then, the light structure and the gas flow of the gas chamber are optimized on Tracepro software and Ansys workbench, respectively, and the technological process for preparing the Micro-Electro-Mechanical System (MEMS) gas chamber is designed. Finally, we produce a gas chamber with a small volume and good transmissivity, which would be the most important part of producing the miniaturized NDIR gas sensor.     

Compact SC frequency tuning circuit for continuous-time Gm–C filters

A novel automatic frequency tuning circuit for continuous-time filters is presented. Based on the switched-capacitor technique, the circuit offers an advantage in terms of simplicity resulting from the use of only two matched current sources, an operational amplifier with relaxed specifications and a transconductor that is a replica of the filter transconductors. Despite the simplicity of the scheme, the accuracy of the system is less than 1 % of frequency error. The circuit has been designed in a 0.5 μm CMOS technology with a 3.3 V power supply and simulation results confirm the suitability of the proposed approach.     

Aperture collimation correction and maximum-likelihood image reconstruction for near-field coded aperture imaging of single photon emission computerized tomography

Coded aperture (CA) imaging originally developed in X-ray astronomy has not been widely used in nuclear medicine due to the decoding complexity of near-field CA images. In this paper, we present a near-field CA imaging technique and image reconstruction method for high sensitivity and high resolution single photon emission computerized tomography (SPECT). Our approach makes three contributions. First, a correction method for the aperture collimation effect is used to eliminate the near-field artifacts without dual acquisitions of mask and anti-mask images. Second, a maximum-likelihood expectation-maximization (MLEM) deconvolution method is used to restore CA images. Finally, a new MLEM-based algorithm is used to partially reconstruct three-dimensional (3-D) objects from a single projection of CA images. Experiments conducted using a dual-head SPECT system equipped with a parallel-hole collimator and a CA module show a tenfold increase in count sensitivity and significant improvement in image resolution with CA collimation as compared to parallel-hole collimation. Experiments conducted using the same dual-head SPECT system equipped with a pinhole collimator show that when the object is closer to the pinhole collimator the CA image resolution is only slightly inferior to the pinhole collimated image. We found that the MLEM deconvolution method provides an inherent nonnegativity constraint on pixel values and remarkably reduces background activities of CA images. The MLEM reconstruction algorithm for CA images is capable of reconstructing 3-D objects from a single projection and can be potentially extended to full 3-D SPECT reconstruction for CA images.     

融合注意力机制与密集多尺度特征的异质噪声虹膜分割方法

针对当前分割方法不能兼顾可见光与近红外光谱的异质噪声虹膜图像的分割精度与效率问题,提出一种基于注意力机制与密集多尺度特征融合的编-解码网络.首先,引入基于深度可分离卷积的改进残差瓶颈单元,降低参数量与计算量的同时防止信息丢失与梯度混淆;其次,改进密集空洞空间金字塔模块的空洞率组合并放置于编码器后,以增强多尺度特征融合;...     

BeWell: Sensing Sleep,Physical Activities and Social Interactions to Promote Wellbeing

Smartphone sensing and persuasive feedback design is enabling a new generation of wellbeing apps capable of automatically monitoring multiple aspects of physical and mental health. In this article, we present BeWell+ the next generation of the BeWell smartphone wellbeing app, which monitors user behavior along three health dimensions, namely sleep, physical activity, and social interaction. BeWell promotes improved behavioral patterns via feedback rendered as an ambient display on the smartphone’s wallpaper. With BeWell+, we introduce new mechanisms to address key limitations of the original BeWell app; specifically, (1) community adaptive wellbeing feedback, which generalizes to diverse user communities (e.g., elderly, children) by promoting better behavior yet remains realistic to the user’s lifestyle; and, (2) wellbeing adaptive energy allocation, which prioritizes monitoring fidelity and feedback responsiveness on specific health dimensions (e.g., sleep) where the user needs additional help. We evaluate BeWell+ with a 27 person, 19 day field trial. Our findings show that not only can BeWell+ operate successfully on consumer smartphones; but also users understand feedback and respond by taking steps towards leading healthier lifestyles.     

LTE中家庭基站的干扰协调

家庭基站是近年来新兴的室内覆盖技术,能以较低的功率为用户提供高速率高带宽的服务,是新一代移动网络与固定网络的一种融合方式。然而家庭基站的密集部署,重叠覆盖会造成复杂的干扰结构。因此,有效的干扰管理技术是家庭基站研究中的关键问题。干扰协调技术被3GPP RAN4工作组认为是解决家庭基站干扰问题的有效方法之一。文章主要分析了家庭基站和现有宏蜂窝基站组成的异构网络的几种典型干扰场景,对家庭基站干扰协调的基本原理进行了说明,并介绍了基于干扰协调原理的典型干扰管理技术在家庭基站干扰控制上的应用,最后对家庭基站干扰管理技术做出了展望。     

小发散角高功率半导体激光器研究

在量子阱半导体激光器中,量子尺寸引起的衍射效应使半导体激光器的光束质量很差。分别限制结构的垂直结平面发散角在40°左右,使得光束整形系统比较复杂,限制了半导体激光器的直接应用。为解决这一问题,提出了降低垂直结平面发散角的要求。回顾了小发散角半导体激光器的技术发展及应用,对具有小发散角的模式扩展波导结构进行了理论模拟和实验验证,获得了优化的结构。采用MOCVD外延技术生长了外延片,制作了高峰值功率脉冲激光器,获得了快轴发散角小于25,°峰值功率大于80W的半导体激光器,在激光引信应用中获得良好效果。