圆锥曲线的光(声)学性质

本文以微分方程为主要工具揭示了圆锥曲线的光(声)学性质。     

Parenting as a Dynamic Process: A Test of the Resource Dilution Hypothesis

In this paper, we tested the resource dilution hypothesis, which posits that, because parenting resources are finite, the addition of a new sibling depletes parenting resources for other children in the household. We estimated growth curve models on the self‐reported parenting practices of mothers using four waves of data collected biennially between 1994 and 2000 on a nationally representative sample of 2,082 Canadian children aged 2 to 5 at initial interview and in continuously intact, two‐biological‐parent households. Results showed that when new children were added to the household, mothers exhibited declines in positive interaction, but increased their levels of consistent parenting. Taken together, these findings suggested that parenting resources were reallocated, rather than diluted, when family size increased.     

流体粘度对涡轮流量计性能影响的理论预测

流体粘度是影响涡轮流量计性能的主要因素之一。本文运用粘性流体力学原理对现有涡轮流量计理论模型进行了改进。根据新模型计算的流量计特性曲线与变粘度实验结果更为吻合,从而为解决工业生产中涡轮流量计测量结果的粘度修正问题提供了实用的方法。利用本文的研究结果还可预测仪表几何参数和来流速度分布等因素对涡轮流量计性能的影响,作为改进仪表设计的理论依据。     

高温回热器传热性能试验研究

采用等流量法对回热器在600℃高温下进行传热性能试验，并利用Origin自定义函数曲线拟合法对试验数据进行处理，得出了具有工程应用价值的Nu-Re准则关系式．     

中美国债收益率比较分析——来自2002—2014 年国债市场的经验证据

国债收益率波动对于一国金融市场配置资源的效率,乃至金融市场的稳定具有重要影响。本文以2002-2014年中美国债市场数据为样本,从国债收益率曲线、收益率波动以及影响因素等方面对中美国债收益率进行了比较研究。结果发现,中国交易所市场和银行间市场国债收益率形态并不一致,中美国债收益率波动也具有各自特征;中美国债收益率对于美元指数变化的反应并不相同,当美元升值时,中美国债收益率表现出一定程度的趋同性,而当美元贬值时,中美国债收益率则表现出一定程度的背离;中美国债收益率对于物价指数变动的反应相同,均与各自国内物价指数间呈现正向关系。基于此,论文从丰富国债交易品种、完善交易机制、发挥国债市场资金价格功能等方面提出了完善我国国债市场发展的政策建议。     

基于单位球面生成的等距双NURBS刀具路径规划

目前由离散刀位点数据生成的2条NURBS曲线刀具路径中,刀轴点NURBS曲线与刀具中心点NURBS曲线间 距有可能存在不相等的问题,提出一种单位球面下优化刀轴矢量NURBS曲线的方法,用以解决生成的等距双NURBS刀 具路径中2条NURBS曲线间距有可能不相等的问题。算例表明,本算法可以对工件坐标系下的线性刀路进行光顺,确 保双NURBS样条曲线的间距相等。     

胶辊数字中高机的设计

针对印刷机中普通胶辊由于胶辊扰度造成印制品厚薄不均的问题,以中高度法原理为依据,提出了将中高度曲 线方程解析成以时间为变量的函数,用单片机计算和控制中高机运动,设计了以单片机、交流伺服控制器、变频器和磨头 等构建的一个数字控制系统为核心的胶辊数字中高机。应用结果表明数字中高机可安装在普通车床上实现中高胶辊的 加工,且中高曲线和中高度可任意设置,设计简便实用,便于推广。     

Planners' Perspectives on Obstacles to Sustainable Urban Development: Implications for Transformative Planning Strategies

A major problem confronting planning is the gap between transformative proposals and enduring urban development trends. The paper interprets interviews with 62 planners involved in a sustainable urban development strategy in a large region focussed on Toronto, Canada. Surveyed planners were asked about the obstacles they encounter when attempting to modify prevailing urban development. Mentioned obstacles are consistent with expectations arising from three major perspectives on inertia: institutionalism, political economy and path dependence. Interviews also highlight the role of planners' practical knowledge in identifying and interpreting obstacles, and the existence of a consensus among respondents over sustainable urban development.     

Detecting diagnostic accuracy of two biomarkers through a bivariate log-normal ROC curve

In biomedical research, two or more biomarkers may be available for diagnosis of a particular disease. Selecting one single biomarker which ideally discriminate a diseased group from a healthy group is confront in a diagnostic process. Frequently, most of the people use the accuracy measure, area under the receiver operating characteristic (ROC) curve to choose the best diagnostic marker among the available markers for diagnosis. Some authors have tried to combine the multiple markers by an optimal linear combination to increase the discriminatory power. In this paper, we propose an alternative method that combines two continuous biomarkers by direct bivariate modeling of the ROC curve under log-normality assumption. The proposed method is applied to simulated data set and prostate cancer diagnostic biomarker data set.