企业财务危机预警双基点距离比值法

本文介绍了国内外主要企业财务危机预警模型,对模型的空间几何意义进行解释。提出了企业财务危机预警双基点距离比值模型,该模型采用非线性方法对危机企业与非危机企业的财务指标集合进行分割。用112例样本实证,预警识别率达到92.8%。     

竹亚科植物过氧化物酶和酯酶同工酶研究

用聚丙烯酰胺凝胶电泳方法分析竹亚科九属二十七种植物过氧化物酶和酯酶同工酶，结果表明：过氧化物酶同工酶谱在种间明显差异，各竹种有特征酶谱。其酶谱特征及酶谱距离可作为竹种分类特征之—，有助于竹种的分类，同时也可了解种间亲缘关系。而酯酶同工酶谱在种间差异小，不宜作竹种的分类特征，但也能反映出种间的亲缘关系。     

中国影子银行违约风险和防范机制研究——来自上市公司委托贷款数据的经验证据

本文运用中国上市公司披露的委托贷款公告数据，实证研究了影子银行的违约风险及其防范机制。数据显示，我国委托贷款的整体违约率为10.09%，远高于同期银行业金融机构的不良贷款率。进一步研究发现，与影子银行风险受信息因素影响的直觉一致，抵押条款和借贷距离会显著影响委托贷款违约率：其一，从抵押视角来看，抵押条款和贷款违约率显著正相关，这表明，为了防范事后的道德风险问题，贷款者会要求借款者提供抵押；其二，从借贷距离视角看，与近距离借贷（或同省借贷）相比，远距离借贷（或异省借贷）的违约风险相对较高，这揭示出，借贷距离越远，贷款者越难对借款者进行甄别和监督，从而推高了借款企业的违约概率。本文研究不仅为我国委托贷款这一影子银行机制的风险状况提供了直接的经验证据，而且对影子银行参与者如何有效防范风险和相关政府部门加强监管具有重要的借鉴意义。     

ROBUSTNESS OF PROCEDURES FOR THE BEHRENS-FISHER PROBLEMS: EXTENSION TO BIVARIATE NORMAL MIXTURES

In the applied sciences, it is often important to be able to compare the mean values of two populations. However, testing a hypothesis can be complex, if the two populations are heteroscedastic and exhibit non-normality in the data. This paper reviews currently available strategies for the multivariate Behrens-Fisher problem. It then carries out Monte Carlo comparisons of selected procedures to assess their robustness when applied to data from normal mixture distributions. The overall conclusion is that Johansen's procedure appears to work best for small sample data both in terms of empirical power and significance level. Johansen's procedure works reasonably well even with mixture data. The simulation also provides researchers with specific guidelines to follow at the early designing and planning stages of the investigation.     

DDS的背景杂散信号分析

采用信号分析的方法，在对相位累加器进行等效的基础上系统地推导出了幅度量化误差（ＲＯＭ舍位）对直接数字频率合成器（ＤＤＳ）频谱分布的影响规律。所得到的理论推导结果与有关文献给出的计算机模拟结果符合较好，进一步完善了ＤＤＳ的理论体系。     

空中防撞系统避撞机制的数学模型

在TCAS系统中,到达最接近点的时间Tau、HMD和VMD是描述空中碰撞物理过程的主要参数,利用该组参数能够完整地描述TCAS系统的防撞机制。该文通过对到CPA时间的近似,引入对Tau时间的物理解释;并通过坐标变换,采用本机和入侵飞机的相对距离、相对距离变化率和相对距离加速度推导出了HMD的数学表达式;分析了工程实际应用中的修正模型。     

Connectivity in urbanizing landscapes: The importance of habitat configuration,urban area size,and dispersal

Human activities affect both the amount and configuration of habitat. These changes have important ecological implications that can be measured as changes in landscape connectivity. I investigated how urbanization interacts with the initial amount and aggregation of habitat to change dispersal potential, restoration potential, and the risk of spatially extensive disturbances. I used a factorial set of simulated landscapes and subjected each landscape to habitat loss by overlaying 66 different US urban areas. I used a common connectivity metric, CONNECT, to assess the magnitude and direction of changes for a range of dispersal distances. My results show that the relationship between habitat loss and connectivity loss is non-linear and subject to interactions between the spatial patterns of habitat distribution, urban morphology, and dispersal capabilities. The implications of a given urban form vary widely as a function of habitat distribution and dispersal capabilities. This implies that impact assessments, restoration activities, and conservation planning should consider historical habitat distribution when evaluating observed changes in connectivity. While my results clearly show that more aggregated or continuous habitats are more vulnerable to connectivity loss, this approach can also be used to identify landscapes where restoring connectivity will be particularly effective, for example through placement of stepping stone habitats.     

Robust Methods of Building Regression Models—An Application to thè Housing Sector

This article studies robustification strategies for the linear model in the presence of outliers. The advantages of an internal analysis of the robustness of least squares for a given sample are pointed out. The application of this methodology is illustrated by building an explicit model of the determinants of rental housing values in the Madrid Metropolitan Area.     

最优的核判别分析用于雷达目标识别

特征提取是雷达目标识别研究中的重要问题,有效、稳健的特征是提高识别率的关键。核判别分析(KDA)是一种抽取非线性特征的有效方法,但它会因为奇异性问题而难以求解。基于子空间投影的思想,给出一种最优的核判别分析(OKDA)方法,用于对雷达目标的距离像进行特征提取,然后采用基于核的非线性分类器对所提取的特征进行分类,实现对雷达目标的识别。分别对仿真和实测距离像进行实验,结果表明该方法具有较好的识别效果。