未来电磁频谱管理对信息通信技术的需求分析

无线电通信的高速发展,使频谱使用越来越广泛,频谱资源日益紧张,为使有限的频谱资源发挥更大的价值,一方面依赖于无线通信技术的进步,开发出频谱利用率更高的应用系统,另一方面要加强频谱的科学管理,将行政管理和科学技术紧密结合。信息通信技术在过去的50年中发展迅速,大量研究证实信息通信技术在管理创新和决策活动中的作用非常明显。文章针对电磁频谱管理技术手段的发展,对信息通信技术的需求做相关分析。     

Mapping the total phosphorus concentration of biosolid amended surface soils using LANDSAT TM data

Conventional methods for soil sampling and analysis for soil variability in chemical characteristics are too time-consuming and expensive for multi-seasonal monitoring over large-scale areas. Hence, the objectives of this study are: 1) to determine changes in chemical concentrations of soils that are amended with treated sewage sludge; and 2) to determine if LANDSAT TM data can be used to map surface chemical characteristics of such amended soils. For this study, we selected two fields in NW Ohio, designated as F34 and F11, that had been applied with 34 and 11 ton acre^− 1 of biosolids, respectively. Soil samples from a total of 70 sampling locations across the two fields were collected one day prior to LANDSAT 5 overpass and were analyzed for several elemental concentrations. The accumulation of Ba, Cd, Cu, S and P were found to be significantly higher in the surface soils of field F34, compared to field F11. Regression equations were established to search for algorithms that could map these five elemental concentrations in the surface soils using six, dark-object-subtracted (DOS) LANDSAT TM bands and the 15 non-reciprocal spectral ratios derived from these six bands for the May 20, 2005, LANDSAT 5 TM image. Phosphorus (P) had the highest R² adjusted value (67.9%) among all five elements considered, and the resulting algorithm employed only spectral ratios. This model was successfully tested for robustness by applying it to another LANDSAT TM image obtained on June 5, 2005. Our results enabled us to conclude that LANDSAT TM imagery of bare-soil fields can be used to quantify and map the spatial variation of total phosphorous concentration in surface soils. This research has significant implications for identification and mapping of areas with high P, which is important for implementing and monitoring the best phosphorous management practices across the region.     

Improvement of sensing characteristics of self‐sensing active magnetic bearings

A winding‐current interference model of self‐sensing magnetic bearings (AMBs) and an improvement technique of position‐sensing characteristics are proposed. In the self‐sensing AMB systems, the electromagnets work not only as actuators suspending the rotor but also as position sensors. The self‐sensing position signal, however, includes errors because of nonlinearity of the magnetic circuits. In the proposed model, the current is directly transmitted to the self‐sensing position signal. This transmission means degradation of the self‐sensing characteristics. This winding‐current interference to the self‐sensing signal is reduced by the proposed compensation method. The characteristics of the proposed self‐sensing method agree well with a reference sensor signal up to over 1 kHz. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(2): 70– 77, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20732 Copyright © 2004 Wiley Periodicals, Inc.     

西安脉冲堆~3He快中子夹心谱仪的方案设计

本文介绍了3He快中子夹心谱仪的气体填充、探测器、三通道数字符合和数据分析处理系统,描述了探测器系统的理论分析及实验标定方法,提出了谱仪符合本底计数的来源,绐出了扣除几种符合本底的理论和实验方法,研究结果表明本工作可指导3He快中子夹心谱仪的深入研究.     

Effect of Initial Frequency Chirp on Supercontinuum Generation in Dispersion-flattened Fibers

. Supercontinuum generation in dispersion-flattened fibers is studied theoretically. It is found that the flat spectral width of the supercontinuum generation in normal dispersion-flattened fiber can be increased from 66 nm to over 100 nm when the absolute value of the initial frequency chirps is increased from zero to 10. It is further found that initial frequency chirps are adverse to flat and wideband supercontinuum generation in anomalous dispersion-flattened fiber, and when the absolute value of the frequency chirps is increased to a certain degree, supercontinuum spectrum even can not be achieved.     

集成微力检测与反馈的双晶片微夹持器

微夹持器广泛应用于微装配、生物、医疗等领域。目前复杂武器装备生产中的微小型结构件及系统的夹持和装配还是依靠现场工作人员的经验决定，因此，有必要对微夹持器进行研究。以双晶片微夹持器为例，针对复杂三维微小型结构件及系统，提出了集成微力检测与反馈的组合式微夹持技术并研制了相应的微夹持器；阐述了微力检测与反馈的基本原理，搭建了面向双晶片压电陶瓷微夹持器的基于半导体应变片的微力检测与反馈电路。通过夹持实验实现了微力信号的测量与检测，为夹持、移动和装配过程中的微力测量提供了条件。     

脉冲中子全能谱测井闪烁探测器响应特性的蒙特卡罗模拟

利用蒙特卡罗方法模拟研究NaI和BGO晶体探测器对不同γ射线的响应。模拟结果表明，BGO晶体的光电峰和第一逃逸峰对计数贡献大，而NaI晶体的逃逸峰贡献大。对于井眼和地层流体分别为油和水砂岩地层，模拟改变NaI和BGO晶体探测器的直径和长度时的非弹性散射γ射线响应能谱，采用不同能窗处理方法对地层流体的分辨能力不同，选取光电峰和第一、第二逃逸峰对应的能量窗时，BGO晶体探测器比NaI晶体探测器测量的C/O（C与O的元素含量比）差值大，但受尺寸的影响不大；采用光电峰对应的能量窗时，BGO晶体探测器测量的C/O差值比NaI的大得多，且随尺寸的增加差值增大；能量道的漂移对C/O值影响较大，而能量分辨率对差值影响相对较小。     

Cell Signal Distribution and Imprint Reliability in FeRAM with Hybrid Bit Line Architecture

We have investigated the cell signal distributions of ferroelectric random access memories (FeRAMs) using newly developed design scheme, hybrid bit line architecture and their reliability against imprint degradation. Since FeRAMs have relatively large signal distributions due to nonuniform ferroelectric storage capacitors, cell signal interference between neighboring bit lines severely degrades the sensing signal margin. In order to remove the cross-talk noise, hybrid bit line architecture is developed, which is a combination of the conventional folded and open bit line schemes. The lifetime against imprint degradation of FeRAM devices is also increased using hybrid bit line architecture.     

Uncertainty in fatigue life prediction of structures subject to Gaussian loads

In this paper we shall concentrate on Gaussian (or close to Gaussian) loads acting on a structure. The goal is to compute a measure of risk for fatigue of a component during a specific time period and the so called “safety index” will be used to combine different types of uncertainties. The presented methodology can be applied in a more general situation of environmental loads which properties may vary with time of the year. The load is assumed to be “locally” stationary such that the mean load is constant (and taken to be zero) but the variance of the load can change slowly with time. Non-stationary hierarchical processes, separable into a stationary Gaussian process and a process describing the load amplitude and period, e.g. processes with Pierson–Moskowitz or JONSWAP spectrum, are treated in detail. The variability of a load, relevant for the fatigue accumulation process, will be described by means of rainflow cycles counted in the load. Moreover, common damage intensity approximations are reviewed and evaluated in a simulation study.     

基于MAS的分布式战场电磁频谱管理系统

为适应联合作战中战场电磁频谱管理分布性、实时性的需求，引入多智能体（MAS，Multi-Agent Systems）理论，建立分布式的战场电磁频谱管理系统原型。该系统通过分布在各区域的信息收集与处理、频率规划与指配和指令生成与发布等智能体的相互协作，共同完成战场电磁频谱管理的决策行为。