量子计算中的六个组合恒等式的证明

证明了量子计算中出现的六个组合恒等式。     

涡流空气分级机“鱼钩效应”的实验研究

文中研究了涡流空气分级机分级过程中由于颗粒细化而导致在Tromp曲线上产生“鱼钩效应",导致分级效率降低。根据实验分析了在涡流空气分级机分级中,分级转笼转速、进口风速、给料固体浓度以及给料粒度对“鱼钩效应”的影响。对减弱粉体分级过程中的“鱼钩效应”、涡流空气分级机的操作,具有一定的指导意义。     

用有限元法分析无缝道岔组合效应

为建立能反映无缝道岔组合实际受力情况的计算、分析模型,基于有限单元法,建立了多组无缝道岔相联结时钢轨纵向力及位移的计算模型,编制了计算软件,并以12号固定辙叉无缝道岔为例,分析了不同联接形式无缝道岔对钢轨附加力及位移的影响.研究结果表明:道岔不同联结形式对钢轨的受力及变形有明显的影响,其组合效应不容忽视,特别是钢轨的位移受组合效应影响很大;随着组合道岔组合数的增加,钢轨附加力及钢轨位移的组合效应也随之增加,但增加幅值逐渐减少.     

热分析动力学的多升温速率等温法及其应用

提出了多升温速率等温法确定热分析动力学可能的机理函数g(α);用迭代的等转化率法求出较为可靠的活化能Ea;在Ea和g(α)的基础上计算出指前因子A.用该法对二水草酸镍(NiC2O4·2H2O)脱水反应的热分析动力学三因子进行了研究,得出Ea为96.55 kJ/mol;A为7.746×107～9.415×107s-1;其对应的机理函数为随机成核和随后生长(Avrami-Erofeer),调节函数Am,其积分形式g(α)=[-ln(1-α)]1/m和微分形式f(α)=m(1-α)[-ln(1-α)]1-1/m,调节因子m=1.55～1.70.用该法求算动力学三因子,结果可靠,重现性较好,具有一定的可比性.     

DS-CDMA中空时多用户检测算法及其性能分析

阐述了空时多用户检测的现状，介绍和分析了空时线性多用户检测算法，盲空时多用户检测等几种主要的空时多用户检测技术，并对几种空时多用户检测方法进行了误码率仿真分析，验证了空时多用户检测可以大大改善DS-CDMA系统的性能。     

Multiple change-points estimation of moving-average processes under dependence assumptions

In this paper, some results of convergence for a least-square estimator in the problem of multiple change-points estimation are presented and the moving-average processes of ρ-mixing sequence in the mean shifts are discussed. When the number of change points is known, the consistency of change-points estimator is derived. When the number of changes is unknown, the consistency of the change-points number and the change-points estimator by penalized least-squares method are obtained. The results are also true for φ-mixing, α-mixing, associated and negative associated sequences under suitable conditions.     

RF channel performance assessment for a multiple carrier millimeter-wave communication system

Channel capacity, system versatility and ease of maintenance are factors of prime concern in future generations of wireless communication systems. As a result, millimeter-wave can offer considerable advantages in providing broadband interface. Nonlinearity and noise effects, including parametric fluctuations, are two significant causes for signal degradation in broadband communication systems. Two methods to assess the performance of an RF channel in a multi-carrier system are described. By measuring the forward transfer function from transmitter IF to receiver IF as the frequency is swept across the channel bandwidth, characteristics such as gain flatness, channel dispersion, and saturation effects are revealed. To evaluate the ability of the communication link in preserving the synchronization between two carriers, their heterodyned spectrum at the receiver IF output is studied. Both measurement methods employ standard equipment and have been found to be effective when applied to a multi-carrier millimeter-wave system with over 1 GHz instantaneous bandwidth.     

多天线OFDM系统的线性优化

从Jakes信道模型出发,用KKT优化方法,从信道部分特性已知的情况推导了多天线OFDM系统中发射机与接收机的线性最优化设计问题。仿真比较了多天线OFDM系统的各个子载波之间采用合作的线性优化与非合作的线性优化两种方法在不同最大多普勒频移和反馈时延下发送符号的均方误差。仿真结果表明,当信道特性部分已知时,子载波之间合作的线性优化较之非合作的线性优化有更小的均方误差。可为存在反馈时延的多天线OFDM系统设计提供指导     

基于DPCA、ATI和MUSIC的动目标检测方法

针对SAR(合成孔径雷达)动目标检测,提出一种DPCA(中心相位偏置天线)、ATI(沿迹干涉)和MUSIC(多信号分类)相结合的三孔径动目标检测方法。该方法首先采用DPCA技术消除杂波干扰、检测运动目标,然后用ATI和MUSIC方法确定目标的位置和速度。理论分析和计算机仿真表明,该方法是有效的,不仅能够检测运动目标,而且能够精确估计其运动参数。     

基于时频域特征和分层决策的通信信号调制识别

针对实际通信信号具有时变、非平稳的特性,将时频分布引入通信信号调制类型识别,提出了新的品质优良的时频域识别特征和使用时频域特征的分层决策分类器。即以基于Wigner Ville分布(WVD)的一阶时间矩特征和基于Margenau Hill分布(MHD)的局部时频域特征作为分类特征向量,通过特征向量与判决阈值的逐层比较以实现通信信号调制分类。仿真结果表明,该方法在低信噪比下的识别性能明显优于基于单纯的时域特征或频域特征的传统方法。