北斗B1信号捕获跟踪算法的软件仿真研究

针对北斗B1频率的I支路信号,设计并实现了北斗软件接收机的基带处理部分。阐述了北斗B1频点信号的扩频体制和产生过程,并行码相位搜索捕获策略以及鉴相辅助跟踪环路,并设计了二阶数字环路滤波器,滤波器参数取ζ=0.707,B_n=25(Hz)。同时采用Matlab软件,仿真北斗中频数字信号,编码实现捕获跟踪算法,并分别通过对仿真信号和真实卫星信号的捕获跟踪,验证捕获跟踪算法的可行性,并提出锁频环辅助锁相环算法的改进思路。为进一步开展北斗软件接收机相关技术研究打下了基础。     

基于信噪比测量的欺骗干扰检测方法

在捕获北斗信号的过程中,接收机根据预先设定好的信号搜捕策略和门限值来捕获信号;欺骗干扰源通过产生虚假的相关峰和增加噪声基底,可以有效地干扰普通型北斗接收机正常的捕获工作;针对欺骗信号检测问题,在分析欺骗信号入侵对接收机噪声基底影响的基础上,提出了在捕获阶段利用信噪比(SNR)检测技术识别欺骗干扰信号的方法,并对其有效性进行了分析;仿真结果表明,采用该方法的接收机具有一定程度的欺骗干扰识别能力,为提高GNSS接收机抗干扰能力提供了有益的参考 。     

STUDY OF THE NUCLEAR PHENOMENA IN THE LOW ENERGY (60-360 keV) PROTON BEAM IMPLANTATION ON METALS

A series of studies on the nuclear interaction and its effects in solids during proton implantation were performed in the energy region between 60 and 360keV. Some charged particle products were observed in the implantation experiments on metal samples such as deuterated titanium, titanium alloy, titanium foil on molybdenum substrate, molybdenum and stainless steel, etc.. The energies of the charged particle products are about 3.9, 5.6 and 8.4MeV, respectively. These particles were identified as alpha particles with both detector telescope and absorption measurements. These three kinds of alpha products were found from different proton sub-barrier reactions. The exciting curve of this reaction increases exponentially with the growth of proton energy in the energy region from 90 to 330keV. The radiation damages induced by the nuclear products in the sample have been studied with scanning electron microscopy technique. The possible surface damages induced by them were observed evidently. The origin of the nuclear reactions and their effect on implantation are discussed.     

27Al+27Al耗散产物反应时间的提取

用发展了的Ericson统计理论,从²⁷Al+²⁷Al碰撞的耗散产物的激发函数提取了反应的相互作用时间约4.3×10^－21s.     

30MeV/u 40Ar+115In反应中的IMF能谱

测量了30MeV/u ⁴⁰Ar束流轰击¹¹⁵In反应靶时出射的中等质量碎片(IMF)的能谱.通过比较在不同出射角度发射的同一种IMF的能谱,得到了IMF的发射机制随出射角的演化关系.在假定运动源速度和出射离子库仑位垒不随出射角变化的条件下,通过改变发射源的强度和核温度参量完成了对实验测得能谱的运动源拟合,并详细讨论了3个发射源所占份额和源强随出射角的演化关系.     

具有通信时延下多无人机编队控制

 针对具有二阶动力学特性多无人机系统模型,在具有通信时延及编队构型时变的情况下,本文提出了一种基于一致性理论的编队控制算法。首先将多个无人机的时变编队控制问题转换成闭环系统的渐近稳定问题;然后通过构造Lyapunov-Krasovskii 函数,并以线性矩阵不等式（linear matrix inequality）的形式给出多无人机编队系统时变编队稳定的充分条件;最后以被视为质点的多无人机系统为例进行了仿真验证。结果表明：当通信时延、控制协议参数等满足稳定条件时,文中提出的编队控制算法能使多无人机编队系统形成期望的时变编队队形。     

Mg2FeH6储氢材料的反应机械合金化合成及其放氢性能

以Mg和Fe元素粉末为原料,在双行星式球磨机的氢气气氛中反应球磨,合成Mg2FeH6储氢材料.探讨分别采用Mg和Fe原料配比为化学计量(2-1)和非化学计量(3-1)直接反应球磨,以及采用将Mg和Fe混合粉末在氩气气氛中预磨20 h后再通氢反应等球磨方式.研究结果表明Mg和Fe以非化学计量比(3-1)在氢气气氛中直接球磨所得样品,Mg2FeH6的合成产率最高,达到83.7%;DSC和TGA测试显示样品实际放氢量为2.91%,Mg和Fe以化学计量比(2-1)直接反应球磨得到的Mg2FeH6具有最低的起始放氢温度204.4 ℃.     

洪泽湖断面水质状况评价及分析

文章运用主成分分析法对洪泽湖6个监测断面的污染因素进行分析研究,根据主成分分析结果对水质污染的综合评价,并结合水质月报为改善洪泽湖水质富营养化恢复湖泊生态环境,提出可行性治理方案。     

重离子耗散反应产物激发函数研究的新进展

评述了近两年多来在重离子耗散反应激发函数研究中新的实验结果与理论进展.重点介绍27Al+2 7Al耗散反应产物的长程角度关联以及19F+93Nb耗散反应中截面及其涨落测量的不可重复性. The experimental study and the theoretical development on the structures of excitation functions in dissipative heavy ion collisions last years were reviewed. Especially the long range angular correlation in the reaction of 27Al+ 27Al and the non reproducibility of the cross sections measured in the reaction of 19F+ 93Nb were introduced. The experimental results indicate that the angular coherent width in the dissipative...     

金属粉末注射成形用石蜡-油-聚乙烯粘结剂

研制了用于Fe-2Ni粉末注射成形的石蜡-油-聚乙烯粘结剂,选择了石蜡和聚乙烯组分,考察了油的加入对组分相容性、生坯强度、粉末装载量、喂料比热容、溶剂脱脂速率的影响.实验结果表明石蜡-油-聚乙烯粘结剂是热力学不相容的体系;油的加入降低了混炼扭矩、最大粉末装载量和生坯强度,但同时也减少了注射缺陷,并使溶剂脱脂速率增大;加入该粘结剂,可使Fe-2Ni粉末装载量(体积分数)达60％,生坯强度达5.5MPa,溶剂脱脂速率大于2mm/h.