Optimal design for interacting blocks with OAVS incidence

Optimal design is studied for multiway cross classifications in which the blocking factors exhibit interaction and in which the incidence structure of the blocking factors describes an orthogonal array. Assuming the orthogonal array to be of sufficient strength (enough to allow orthogonal estimation of all of the interaction terms), easily used forms of the information matrix for treatment estimation are derived, and optimality conditions are stated. Some illustrative construction examples are given.     

On the linear statistical relationship

The fitting of lines to data, when the relative precision of the measured data is a known constant, is a problem which is of some interest, for example in comparison of measurement procedures. We examine some ways of treating this problem with a view to clarifying the relationship of solutions with the Maximum Likelihood Estimate. Acknowledgement. I am grateful to Hans Schneeweiss for suggesting a strengthened form of the definition of f in Section 4.     

粉煤灰的改性及对废水中氨氮处理条件的优化

选用碳酸钠、氢氧化钠和硫酸作为改性剂,对粉煤灰进行改性,通过其去除污废水中氨氮的去除率,确定了氢氧化钠作为改性剂的效果最好,其用量为3 mol/L,之后利用正交设计的方法,优化出粉煤灰处理污废水中氨氮的最佳条件,改性粉煤灰投加量2 g,搅拌温度35℃;溶液pH值为7;搅拌时间30 min．     

Projection‐Based Inference in Randomised Clinical Trials

Covariate information is often available in randomised clinical trials for each subject prior to treatment assignment and is commonly utilised to make covariate adjustment for baseline characteristics predictive of the outcome in order to increase precision and improve power in the detection of a treatment effect. Motivated by a nonparametric covariance analysis, we study a projection approach to making objective covariate adjustment in randomised clinical trials on the basis of two unbiased estimating functions that decouple the outcome and covariate data. The proposed projection approach extends a weighted least‐squares procedure by projecting one of the estimating functions onto the linear subspace spanned by the other estimating function that is E‐ancillary for the average treatment effect. Compared with the weighted least‐squares method, the projection method allows for objective inference on the average treatment effect by exploiting the treatment specific covariate–outcome associations. The resulting projection‐based estimator of the average treatment effect is asymptotically efficient when the treatment‐specific working regression models are correctly specified and is asymptotically more efficient than other existing competitors when the treatment‐specific working regression models are misspecified. The proposed projection method is illustrated by an analysis of data from an HIV clinical trial. In a simulation study, we show that the proposed projection method compares favourably with its competitors in finite samples.     

一种新的定时和频偏联合估计算法

提出了一种新的正交频分复用(OFDM)系统定时和频率同步联合算法。该算法仅需要一 个训练符号就可以完成定时和频偏估计,额外开销量小,定时和频率同步的实现均在时域进 行,简化了同步实现的复杂度。由于使用自相关处理,定时同步对频率偏差具有较强的鲁棒 性。与以往的定时同步算法相比,该算法避免了定时平台和多峰值的出现,即使在非常低 的信噪比下,其定时测度都是一个尖脉冲。仿真结果表明,该算法能快速地实现定时和频率 同步。     

基于OMP分解的宽带Chirp信号多参数估计

将信号稀疏分解——正交匹配追踪(Orthogonal Matching Pursuit,OMP)引入到阵列 信号处理领域,在OMP分解的基础上,提出了宽带Chirp信号多参数估计方法。首 先根据宽带Chirp信号形式建立过完备原子库,对阵列接收信号在该过完备原子库上利用 OMP做稀疏分解,从而由最佳匹配原子的参数获得信号的起始频率和调频斜率的估 计,得到宽带Chirp信号形式。在此基础上,再根据阵列结构和已获得的宽带Chirp信号形式 建立另一个原子库,通过计算阵列接收数据与原子库中原子之间的互相关矩阵的迹,搜索迹 的最大峰值找出最匹配的原子,进而由最佳原子的参数获得信号的波达方向角度（Directio n of Arrival, DOA）的估计。仿真实验证明了该算法对参数估计的有效性,并且表明与WVD ( Wigner Ville Distribution)方法相比,该方法能更有效地对信号的波达方向角度进行估 计。     

战术宽带网络波形物理层解决方案

分析了地面移动台（GMR）的核心波形架构和体制,结合其在军事上的应用发展趋势,给出了宽带战术组网波形物理层解决方案,并剖析了基于正交频分复用（OFDM）的物理层波形的两个核心技术。首先,在峰均比抑制方面,提出基于凸优化集理论,优化的内点算法求解方式解决了传统的迭代限幅滤波技术需要迭代次数高的问题;另一方面,采用基于非统计信息的信道估计方法替代原有的基于最小均方误差(MMSE)的一类方法,仿真结果表明其性能与MMSE基本相当,却避免了计算信道统计信息及矩阵求逆过程中的大量复杂运算。在信道模型下的仿真计算结果表明,提出的物理层方案及关键技术的解决方法具有良好的性能与实用性。     

广义空间调制系统的低复杂度检测算法

针对广义空间调制（GSM）系统接收端最大似然（ML）检测算法计算复杂度极高的缺点,提出了一种基于压缩感知（CS）信号重构理论的低复杂度信号检测算法。首先,在多输入多输出（MIMO）信道模型下,通过改进正交匹配追踪（OMP）算法,得到一个激活天线索引备选集;然后,利用ML算法在该备选集中进行遍历搜索,检测出激活天线索引和星座调制符号。仿真结果表明所提算法的检测性能接近于ML算法,且复杂度约为ML算法的2%。因此,所提算法在保证检测性能的同时也大大降低了计算复杂度,实现了检测性能与复杂度之间的平衡。     

一种新的MIMO无线通信空时分组码方案

从MIMO(多入多出)引出空时分组码背景;针对实际MIMO应用提出了一种利用广义复正交方法新设计的满分集的码率为1/2的6个发射天线4个接收天线(6×4)和8个发射天线4个接收天线(8×4)结构的空时分组码系统,仿真结果表明该系统具有良好性能。     

改良单质硅溶解法制备大粒径硅溶胶的研究

在一定的温度和压力条件下,采用单质硅溶解法,用正交试验法研究了反应温度、反应压力、反应时间、氢氧化钠及硅粉用量等对硅溶胶收率及粒径的影响。实验结果表明,硅溶胶制备实验的最佳工艺条件如下:压力为0.5 MPa,在200 mL去离子水中加入15 g硅粉和0.4 g氢氧化钠,并控温度为160℃反应9 h,在此条件下制得的硅溶胶平均粒径为174.4 nm,收率为80.15%。平行实验结果表明,该最佳工艺条件具有良好的重现性。