双RCD箝位的双管正激变换器研究

针对传统单管和双管DC-DC变换电路分别存在的高开关应力与低占空比的不足,提出一种双RCD箝位的双管正激变换电路,并对该电路进行了稳态分析及仿真与样机试验验证。结果表明,该电路不仅可将最大可调占空比由普通双管时的0.5提升至0.8左右,而且能使最大开关应力较单管有大幅下降,同时,系统具有开关应力低和可调占空比高的优点。     

基于需求链的协同商务模型研究

深入研究了需求链管理和实施中面临的问题,分析了将协同商务引入需求链管理的必要性和必然性,并在此基础上,提出基于需求链管理的四层协同商务模型.模型利用网格技术搭建信息共享平台,充分利用网格技术的分布性、高效性、跨平台性等特点,有效共享实时信息.并在此信息共享平台之上,构建协同作业层、协同管理层以及协同预测层,实现面向需求链的企业联盟的ERP、CRM系统的集成,实现企业间生产、销售、库存、物流等方面的协同管理.     

基于动态联盟的双单元制造模式研究

通过对敏捷制造以及动态联盟生产模式特点的分析,提出了一种基于动态联盟的双单元制造模式,详细讨论了此生产模式的具体组织结构特点,运行方式以及提出的理论与现实依据等问题,最后,对有关问题进行了总结。     

UWB定位系统FPGA基带处理设计

基于到达时间差(TDOA)算法,设计了一个脉冲超宽带(IR-UWB)室内定位系统的原理验证样机。主要介绍传感器捕捉标签发送的IR-UWB窄脉冲,进而测出窄脉冲到达传感器时刻的方法。利用FPGA中数字时钟管理器(DCM)的相移器功能模块(PS)构成延迟锁相环(DLL),测得到达传感器的窄脉冲相对于同步时钟的时刻。原理验证系统定位精度优于40cm,达到设计要求。     

In situ-measured primary production in Lake Superior

Water column primary production is a major term in the organic carbon cycle, particularly in large lakes with relatively reduced shoreline and near-shore influence. Presently, there is a large imbalance in the known inputs vs. outputs of organic carbon in Lake Superior. This study examined primary production in offshore Lake Superior using in situ incubations over a range of conditions representing an annual cycle. Primary producers were dominated by small (< 20 μm) cells and included a relatively large abundance of small, spherical flagellates. During conditions with a warm surface layer, chlorophyll concentrations were two- to three-fold higher within the deep chlorophyll maximum (DCM) than at the surface. Volumetric production (mass L^− 1 d^− 1) was maximal at 2-10 m depth, well above the typical DCM depth. On average, 22% of ¹⁴C label appeared in the dissolved pool at the end of the incubation period with the rest appearing in GF/F-strained particles. A statistical model for volumetric production explained 93% of the variance in individual measurements for depths > 2 m, using temperature and light as predictors. This model was applied to annual fields of temperature and light, and a new estimate for whole-lake annual primary production, 9.73 Tg y^− 1, was derived. This combination of new measurements and modeling results brings the organic carbon cycle of Lake Superior closer to being balanced.     

一种适合于开关稳压器的新颖电流检测方法

针对开关稳压器中负载电流检测难以同时做到准确、同步和结构简单这一难题,结合自己多年工作经验,提出了一种新颖的开关稳压器负载电流检测的新方法。其基本原理是利用断续模式（DCM）下负载电流与同步管栅极驱动信号N_DRV的同步关系,通过检测该栅极信号来检测开关稳压器的输出负载电流。这种方法不仅使负载电流检测同步和准确,且同时克服检测电感平均电流带来的电路结构复杂及实现上的困难。该电路经过HSpice仿真验证,其仅消耗5μA的静态电流,工作状态良好。     

Dispersion compensation optical fiber modules for 40 Gbps WDM communication systems

Dispersion compensation was originally proposed to equalize pulse distortion.With the development of wavelength division multiplexing (WDM) techniques for large capacity optical communication systems,dispersion compensation technologies have been applied into the field.Fiber-based dispersion compensation is an attractive technology for upgrading WDM communication systems because of its dispersion characteristics and good compatibility with transmission optical fibers.Dispersion compensation fibers and the modules are promising technologies,so they have been receiving more and more attention in recent years.In this work,high performance dispersion compensation fiber modules (DCFMs) were developed and applied for the 40 Giga bit-rate systems.First,the design optimization of the dispersion optical fibers was carried out.In theory,the better the refractive index profile is,the larger the negative dispersion we could obtain and the higher the figure of merit (FOM) for the dispersion optical fiber is.Then we manufactured the fiber by using the plasma chemical vapor deposition (PCVD) process of independent intellectual property rights,and a high performance dispersion optical fiber was fabricated.Dispersion compensation fiber modules are made with the dispersion compensating fibers (DCFs) and pigtail fibers at both ends of the DCFs to connect with the transmission fibers.The DCFMs present the following superior characteristics:low insertion loss (IL),low polarization mode dispersion,good matched dispersion for transmission fibers,low nonlinearity,and good stability for environmental variation.The DCFMs have the functions of dispersion compensation and slope compensation in the wavelength range of 1525 to 1625nm.The experiments showed that the dispersion compensation modules (DCMs) met the requirements of the GR-1221-CORE,GR-2854-CORE,and GR-63-CORE standards.The residual dispersions of the G.652 transmission lines compensated for by the DCM in the C-band are less than 3.0ps/nm,and the dispersion slopes are also compensated for by 100%.With the DCFMs,the 8×80km unidirectional transmission experiments in the 48-channel 40Gbps WDM communication system was successfully made,and the results showed that the channel cost was smaller than 1.20dB,without any bit error.     

某援疆干部公寓楼基坑支护方案数值模拟分析

以喀什市某援疆干部公寓楼基坑支护为工程依托,对采用水泥土搅拌桩墙支护基坑进行数值模拟,通过模拟计算结果分析,指出采用水泥墙桩墙支护时,在基坑开挖初期坑底隆起较明显,而后期则是水平位移占主导地位。     

水泥土挡墙位移的计算方法

将水泥土挡墙简化为竖直放置的弹性地基梁，对作用于挡墙上的土压力按荷载函数进行处理，在此基础上建立了水泥土挡墙挠曲变形的微分方程，进而给出了一种计算水泥土挡墙位移的有效方法。     

电缆隧道穿越对高速公路影响的数值分析研究

本文以宁波澄浪电缆隧道工程为研究背景,采用基于位移控制法(DCM)的有限元法分析顶管隧道穿越对高速公路的影响规律。建立了隧道与高速公路的三维有限元模型,用弹塑性本构材料模拟软土,用DCM法模拟隧道开挖引起的地层变形。有限元分析结果表明,三维动态DCM法可以有效模拟隧道掘进对周边环境的影响,而且当地层损失率为1%时,高速公路的最大沉降为0.76cm。研究成果可为实际施工地层损失率控制值选取提供参考。