Application of Zero Correlation Zone Sequences in Quasi-synchronous CDMA Systems

In a quasi-synchronous code division multiple access （QS-CDMA） system, the correlation functions around the origin influence the system performance and odd functions are as important as the even functions. Three kinds of zero correlation zone（ZCZ） sequences are used to analyze and compare the correlation functions. Binary phase shift keying（BPSK） simulations of QS-CDMA system with the three kinds of QS sequences as spreading codes on additive white Gaussian noise（AWGN） channel show that these sequences are quasi-orthogonal, so they are suitable for QS-CDMA system. The correlation between the system performance and the zero correlation zone of the sequence is also proved.     

一种改进的数字水印算法

传统的混沌水印置乱方案存在的两类不足:抗混沌预测技术的能力和有限字长效应的影响。基于混沌序列良好的保密性能,提出了一种改进的随机性很强的混沌水印生成方案。同时,文中在原有的抖动调制水印算法中,加入了奇偶校验编码、译码以及纠错的过程。实验结果表明这些改进能够很好的提高水印的鲁棒性。     

选择性映射算法中的相位序列研究

降低峰值平均功率比是实现正交频分复用(OFDM)系统的一个关键性技术,目前主要有限幅类,编码类和概率类。概率类被认为是一种比较理想的技术,本文研究的选择性映射就是其中的一种。选择性映射需要传输边带信息从而使得频带利用率下降,系统复杂度增加。针对这点对改进的相位序列进行了研究分析,从仿真结果可以得到,这种单极随机相位序列可以有效的降低系统的峰值平均功率比,但是却存在计算量大的缺点。     

短波突发通信快速同步技术研究

对PN序列的捕获问题,介绍了串行捕获和并行捕获两种方案,在此基础上介绍了一种改进的门限自适应的快速同步技术,适用于短波高速数据传输。     

振荡生成器

文章基于GF（2）上一条m-序列，给出一类新型的伪随机序列生成器——振荡生成器。并进一步给出了简化模型，且生成序列具有大周期和高线性复杂度．其简化模型生成序列周期和线性复杂度分别达到（2^m-1）^2和m（2^m-1），稳定性良好，适于在密码系统中使用。     

Effects of ion implantation on the mechanical behavior of GaN films

The effects of ion implantation on the response to indentation in epitaxially grown hexagonal GaN films were studied by means of the static microindentation technique, utilizing Knoop and Vickers indenter geometries. Mg, O, Au, Xe and Ar ions were used as projectiles for the implantation process. Heavily damaged polycrystalline epilayers showed enhanced microhardness values and normal indentation size effect (ISE). Amorphised epilayers showed lower microhardness values, while they presented reverse ISE. The shape of the Knoop indentation print as a function of the implanted species revealed that reverse ISE is connected with plastic behavior. Implantation was also found to render films more receptive to fracture. Normal ISE curves were explained using models such as Meyer's law, Hays-Kendall approach, proportional specimen resistance (PSR), modified PSR and elastic/plastic deformation (EPD) models.     

Junction formation of CuInSe2 with CdS: A comparative study of “dry” and “wet” interfaces

The junction formation of polycrystalline CuInSe₂ absorbers (CIS) with thermally evaporated CdS was investigated by high-resolution synchrotron X-ray photoelectron spectroscopy. The chemistry and electronics of the interfaces of Cd partial electrolyte treated CIS (“wet” processed) and clean, decapped CIS (“dry” processed) were compared. A valence band offset of 0.96(10) eV was determined in both cases. The Cd(Se,OH) surface layer induced by the wet Cd partial electrolyte process does not significantly modify the band alignment at the CIS/CdS heterointerface from the “dry”, vacuum-processed CIS/CdS interface.During the stepwise interface formation the energy converting capability of the CIS/CdS heterojunction was assessed by in situ surface photovoltage measurements at room temperature. The evolution of the surface photovoltage significantly differs for the “wet” and the “dry” interfaces and is discussed in relation to the function in solar cell devices.     

分步重复自动对准光刻工艺技术研究

介绍了投影光刻机的分步重复自动对准光刻系统,分析了其工作原理;从对准标记的设计、工艺与对准的关系两方面进行了论述,阐述了采用这类自动对准系统的光刻机可能遇到的工艺问题,并提出了相应的解决措施.     

一种平衡Gold序列的生成方法

m序列和Gold序列是移动蜂窝通信中作为地址码的常用伪随机序列。介绍了m序列的基本生成原则,设计了一种平衡Gold序列的生成方法,并经Matlab仿真,证实了此方法的有效性。     

基于转动的光纤陀螺捷联系统初始对准研究

基于某型低精度光纤陀螺捷联系统,分别采用经典罗经对准、两位置卡尔曼滤波及连续旋转卡尔曼滤波三种方法进行了初始对准实验研究。结果表明,经典罗经对准方法由于未对零偏进行处理,导致其精度不高。两位置卡尔曼滤波方法可以对惯性器件的零偏进行估计并补偿,一定程度上提高了精度。连续旋转卡尔曼滤波方法通过调制抑制陀螺零偏误差影响,相比前两种对准方法,精度显著提高,该文进行了理论分析。