基于现金流量的企业财务预警实证研究——来自我国房地产业上市公司数据

财务危机是威胁企业持续经营的根本性危机,财务预警作为经济运行的晴雨表和企业经营的警示灯,在全球金融危机后其重要性更加凸显。现金是企业的血液,现金流量信息作为企业实体资源和财务状况最直接的反映,对企业财务危机具有较强的财务判别和预警能力。本文以现金流量指标对房地产企业进行实证研究,建立房地产业的现金流财务预警模型并检验其预测财务危机能力,为房地产企业提供可操作的规避财务风险的思路。     

The Game of Contacts: Estimating the Social Visibility of Groups

Estimating the sizes of hard-to-count populations is a challenging and important problem that occurs frequently in social science, public health, and public policy. This problem is particularly pressing in HIV/AIDS research because estimates of the sizes of the most at-risk populations-illicit drug users, men who have sex with men, and sex workers-are needed for designing, evaluating, and funding programs to curb the spread of the disease. A promising new approach in this area is the network scale-up method, which uses information about the personal networks of respondents to make population size estimates. However, if the target population has low social visibility, as is likely to be the case in HIV/AIDS research, scale-up estimates will be too low. In this paper we develop a game-like activity that we call the game of contacts in order to estimate the social visibility of groups, and report results from a study of heavy drug users in Curitiba, Brazil (n = 294). The game produced estimates of social visibility that were consistent with qualitative expectations but of surprising magnitude. Further, a number of checks suggest that the data are high-quality. While motivated by the specific problem of population size estimation, our method could be used by researchers more broadly and adds to long-standing efforts to combine the richness of social network analysis with the power and scale of sample surveys.     

两区复合油藏二次梯度非线性渗流模型研究

考虑二次压力梯度影响的非线性渗流模型比常规线性模型更能准确反映地下原油在油藏中的渗流规律。针对两区复合油藏，从达西定律、质量守恒原理出发，结合状态方程，推导出了考虑二次压力梯度影响的渗流方程，建立了二次压力梯度两区复合油藏非线性渗流试井模型。通过变量代换，将渗流方程线性化，求得Laplace空间解析解，利用数值反演获得实空间解，从而绘制出带二次压力梯度影响的两区复合油藏试井样版曲线，对不同参数进行了敏感性分析。误差分析表明二次压力梯度影响不应被忽略。     

用淬冷法确定饱和液氮中的池沸腾热流密度曲线

用直径为５０ｍｍ、厚度为１２ｍｍ的铜平板在液氮中进行了不同热面方位角的淬冷沸腾实验，各方位角为θ＝０°（热面向下）、１０°、２０°、３０°、５０°和９０°（热面垂直）；随着方位角的增加，临界热流密度、最小膜态沸腾热流密度及其壁面过热度相应地增加，且在方位角θ＜３０°时，θ对上述参数的影响更大；得出ｑＣＨＦ、ｑｍｉｎ与方位角的关系式．     

旋转三维紊流流场的数值分析

应用SIMPLEST方法和标准k-ε紊流模型对旋转直通道内的流场进行计算，给出了该旋转流场的速度矢量图及压力场，并将测量截面上的主流和二次流速度分布与实验值作了对比，结果吻合较好，对叶轮机械内的旋转流场的数值模拟有重要意义。     

在线镉柱还原-流动注射分析法测定水中硝酸盐/亚硝酸盐氮

采用在线镉柱还原-流动注射分析法同时测定水中的硝酸盐氮和亚硝酸盐氮。其中硝酸盐氮的方法线性范围为20.0-2000.0μg/L,相关系数r≥0.999,检出限为1.1μg/L,相对标准偏差为0.97%,样品测定频率为22样/小时,实际水样的加标回收率为94%-106%。亚硝酸盐氮的方法线性范围为2.0-200.0μg/L,相关系数r≥0.999,检出限为0.4μg/L,相对标准偏差为0.35%,样品测定频率为27样/小时,实际水样的加标回收率为91%-109%。此方法简单快捷,对于实际水样的测定结果令人满意。     

When good is good: A virtuous circle of self-efficacy and flow at work among teachers

Abstract

The objective of this study was to extend the channel model of flow (Csikszentmihalyi, 1975, 1990) by including self-efficacy as predictor of the challenges-skills combination, and of the flow experience itself, based on the predictions of social cognitive theory (Bandura, 1997, 2001). We conducted a two-wave longitudinal study among 258 secondary school teachers. Results, first, showed that the channel model of flow, including self-efficacy as antecedent of flow, fitted better the data. Secondly, it was observed that the more self-efficacy the more flow frequency and higher levels of challenge and skills which, in turn, predicted flow over time. Moreover, the influence of self-efficacy on flow over time was mediated by subjects' perception of the challenges and skills combination. Finally, we discuss the theoretical and practical implications of integrating flow theory into the social cognitive theory.     

应力敏感气藏产能方程研究

针对应力敏感气藏开发存在变渗透率的问题，定义了新的考虑应力敏感的拟压力，并从气体多孔介质渗流力学理论出发，建立了考虑应力敏感影响的气藏二项式产能方程，讨论了该方程参数     

健跳南港区疏港公路连接线周边海域流场的数值模拟

敏感海岸的建设工程,会引起周边海域的水动力改变。运用基于三角形网格有限元模式的数学模型,模拟了疏港公路跨海湾的大桥和路堤修建后所引起的周边海域水动力的变化情况。结果表明,这种模式能较好地模拟地形复杂水域的水动力场,可用于预测海岸工程建设后所引起的流场变化,对今后计算模型的选择具有一定的借鉴作用。     

试论大学的流动

大学流动有其特定的含义、性质和类型。衡量一所大学是向上还是向下流动,主要的方式是对大学进行评价。大学流动受制于众多的内部与外部、主观与客观因素,弄清这些制约因素,有利于大学流动的健康发展。