The maximal {-1,1}-determinant of order 15

We demonstrate the D-optimality of the 15×15 −1,1-matrix discovered independently by Smith and Cohn. This matrix has determinant 25515×2¹⁴ and is unique up to Hadamard equivalence. In addition, we confirm the previously established values of the maximal determinant for all other odd orders up to 21, excluding 19, and we improve the upper bounds on the maximal determinant in orders 29, 33, and 37.     

The Role of Pension Business Benefits in Institutional Block Ownership and Corporate Governance*

We investigate whether potential pension contracting benefits lead institutions that provide pension services to acquire ownership blocks in firms and the implications of such blockholdings on the firms' corporate governance. We use the 2006 Pension Protection Act, which expanded pension participation in certain states, as a quasi-exogenous shock and find an increase in block ownership by pension-providing institutions in firms with substantial operations in affected states. Further, we find that the acquisition of a large block increases the likelihood that the institution will provide future pension services to the firm. With regard to corporate governance, we find that the acquisition of large pension blockholdings is associated with higher CEO pay and lower CEO turnover following poor financial performance. However, contrary to the prediction of the private benefits hypothesis, we do not find consistent evidence that large pension blockholdings are associated with declining firm profitability, suggesting that pension institutions are incentivized to exert monitoring to preserve the investment value of their blockholdings. Overall, our evidence is consistent with pension service institutions acquiring ownership blocks to obtain pension contracts, but our evidence does not support the prediction that they use their influence to compromise shareholder value.     

Further empirical evidence on block transactions below the MBR: the Spanish market

There is a relatively unknown market for partial control or corporate influence in Spanish listed firms, where the control transaction size is below the legal threshold that triggers a mandatory tender offer, as this kind of deal looks for exercising some degree of control, but not a full control. The goal of this paper is to go further in its empirical analysis by exploring its distinguishing features, using as the criterion to define its transactions obtaining a seat in the board of directors. We find that these deals are mainly located in the segment of the market of large trades where the rules for private negotiations are easier to implement; the size of the block is relatively large and it is negotiated as a whole block. Besides, the most common buyer has no previous stake in the firm. We find no evidence that the buyers pay, in median, for a seat on the board of directors, but the variability of the premiums for those blocks is higher and shows that buyers that had no control position in the target firm pay more for being among largest shareholders (partial control) and less for not being among them (influence).     

Quasi-longitudinal Designs in SEM state Space Modeling

The collection of longitudinal data over the full model time scope is often an appropriate way to estimate the dynamic state space model with time-varying parameters. Nevertheless, in many situations it is possible and preferable to collect and combine data from independent groups of subjects, each covering a shorter interval than the full dynamic model. Several quasi-longitudinal designs are discussed: overlapping designs (overlapping cohort design OCD and overlapping samples design OSD) as well as nonoverlapping designs up to the exclusively cross-sectional design. The use of the structural equation modeling (SEM) program Mx and continuous time state space modeling is recommended. Finally, a number of the quasi-longitudinal designs is empirically evaluated, comparing the results with those of the full-longitudinal design.     

基于Turbo-TCM与时空分组码的级联系统的次优译码算法

针对瑞利信道中存在的严重的多径衰落，本文实现了Turbo-TCM方案与时空分组码的级联系统，以期利用空间分集改善系统的误码率性能。针对级联系统的译码，本文给出了一种具有低译码时延的次优译码算法，该算法的特点是各模块独立译码，先算比特对数似然比再进行二进制Turbo码译码。最后通过计算机仿真给出了使用该次优译码算法的Turbo－TCM方案与时空分组码的级联系统的译码性能。仿真结果说明，当发射天线数目一定时，随着接收天线数目的增加，译码性能的增益随之增加而帧长对译码性能的影响则随之减小。     

大河矿区下草坪矿段构造特征及其对煤层稳定性的影响

文章主要对矿区内的含煤地层特征、构造特征、构造对煤层影响等进行了认真地分析研究,认为本区的总体构造形态为向斜与背斜构成的复合构造,断层对煤层稳定性影响表现为中等,对煤层开采影响较大。这一研究为今后周边矿区地质勘探及煤炭开发提供了理论依据。     

Relevance weighted likelihood for dependent data

The relevance-weighted likelihood function weights individual contributions to the likelihood according to their relevance for the inferential problem of interest. Consistency and asymptotic normality of the weighted maximum likelihood estimator were previously proved for independent sequences of random variables. We extend these results to apply to dependent sequences, and, in so doing, provide a unified approach to a number of diverse problems in dependent data. In particular, we provide a heretofore unknown approach for dealing with heterogeneity in adaptive designs, and unify the smoothing approach that appears in many foundational papers for independent data. Applications are given in clinical trials, psychophysics experiments, time series models, transition models, and nonparametric regression. Received: April 2000     

Finding Bayesian Optimal Designs for Nonlinear Models: A Semidefinite Programming‐Based Approach

This paper uses semidefinite programming (SDP) to construct Bayesian optimal design for nonlinear regression models. The setup here extends the formulation of the optimal designs problem as an SDP problem from linear to nonlinear models. Gaussian quadrature formulas (GQF) are used to compute the expectation in the Bayesian design criterion, such as D‐, A‐ or E‐optimality. As an illustrative example, we demonstrate the approach using the power‐logistic model and compare results in the literature. Additionally, we investigate how the optimal design is impacted by different discretising schemes for the design space, different amounts of uncertainty in the parameter values, different choices of GQF and different prior distributions for the vector of model parameters, including normal priors with and without correlated components. Further applications to find Bayesian D‐optimal designs with two regressors for a logistic model and a two‐variable generalised linear model with a gamma distributed response are discussed, and some limitations of our approach are noted.     

论施工组织设计与工程造价

建筑施工企业要想在激烈的市场竞争中立于不败之地，提高生存能力和竞争力，不但要具有雄厚的施工实力，而且还要拥有较高的施工管理水平和组织能力。文章从施工企业投标的角度，论述怎样优化施工方案。积极响应业主招标文件编制先进科学、投标报价合理、业主易于接受的投标文件。     

一种低复杂度的CPM信号最大似然块检测算法

为了降低连续相位调制(Continuous Phase Modulation,CPM)信号多符号非相干检测的运算复杂度，提出了一种低复杂度的最大似然块检测算法。该算法充分利用已判决输出的符号对检测过程中的符号向量取值进行约束，有效减少判决统计量计算时的运算量，进而降低算法复杂度。另外，该算法引入判决长度变量，通过调整单次检测时判决符号数使算法能够在检测性能与运算量之间灵活折中。仿真结果表明，提出的低复杂度检测算法能够适用于全响应和部分响应CPM信号，相比原最大似然块检测算法能够在不损失检测性能的前提下降低算法运算量至少50〖WT《Times New Roman》〗%〖WTBZ〗，并且能够通过选择不同的判决长度提高算法应用的灵活性。