Neighborhood change from the bottom Up: What are the determinants of social distance between new and prior residents?

An important source of neighborhood change occurs when there is a turnover in the housing unit due to residential mobility and the new residents differ from the prior residents based on socio-demographic characteristics (what we term social distance). Nonetheless, research has typically not asked which characteristics explain transitions with higher social distance based on a number of demographic dimensions. We explore this question using American Housing Survey data from 1985 to 2007, and focus on instances in which the prior household moved out and is replaced by a new household. We focus on four key characteristics for explaining this social distance: the type of housing unit, the age of the housing unit, the length of residence of the exiting household, and the crime and social disorder in the neighborhood. We find that transitions in the oldest housing units and for the longest tenured residents result in the greatest amount of social distance between new and prior residents, implying that these transitions are particularly important for fostering neighborhood socio-demographic change. The results imply micro-mechanisms at the household level that might help explain net change at the neighborhood level.     

曲柄群驱动机构单元化平衡

为实现曲柄群驱动机构的模块化设计与生产，定义曲柄单元为该机构的基本单元，以曲柄单元为基础研究曲柄 群驱动机构模块化设计中的摆动力平衡问题。研究了影响平衡块质量及配置位置的因素。分析表明，当在所有曲柄的 反方向配置参数相同的平衡决时，平衡决的质量矩与机构中的曲柄个数，曲柄的质量与长度，运动连杆总质量有关。得 出一种满足模块化设计与生产的方法，该方法能快速有效地实现曲柄群驱动机构单元化平衡     

Lagrange multiplier unit root test in the presence of a break in the innovation variance

We show that the Lagrange multiplier (LM) unit root test exhibits size distortions when a break in the innovation variance exists but is ignored. We develop a modified LM unit root test that is based on a generalized least-squares transformation of the original series. The asymptotic null distribution of the new modified LM unit root test is derived. Finite-sample simulation evidence shows that the modified LM unit root test maintains its size and has reasonable power against the trend stationary alternative.     

Moderate Deviation Principles for Empirical Covariance in the Neighbourhood of the Unit Root

In this paper, we consider the linear autoregressive model with varying coefficients θ_n∈[0,1). When θ_n tending to the unit root, the moderate deviation principle for empirical covariance is discussed, and as statistical applications, we provide the moderate deviation estimates of the least square and the Yule–Walker estimators of the parameter θ_n.     

Small-Sample Improved Seasonal Unit Root Tests for Trending and Breaking Series

In this article three unit root tests that allow for a break in both the seasonal mean and linear trend of the data are proposed. The tests, which can be seen as small-sample corrected versions of already known asymptotic tests, are shown to perform very well in simulations, and much better than their asymptotic counterparts.     

Factors Affecting Planned Unit Development Implementation

Planned unit developments (PUD) have been celebrated as one of the few means of escape from the stranglehold of Euclidean zoning but little is known empirically about their use and implementation. In this paper, I present quantitative data from Michigan exploring the factors affecting successful PUD implementation. Results indicate that citizen participation, emphasis of PUD regulations, PUD appeal and differences among key players during PUD review have significant impacts on successful PUD implementation. I also find that Michigan municipalities are more successful at achieving mixed-use, density, preservation, affordable housing, community facilities and design through PUDs than through other regulatory vehicles.     

不同类型研究机构卫生技术评估研究结果转化情况的比较研究

目的:通过对不同类型研究机构的卫生技术评估(HTA)研究结果转化情况的比较,为扩大HTA的决策使用提供科学依据?方法:采用自设问卷,开展针对国内HTA研究者的问卷调查,通过Likert 五分法描述HTA研究结果转化情况,运用秩和检验进行差异分析?结果:虽然在HTA转化利用方面的差异尚无统计学意义,但在组织支持?研究过程?认知水平?研究产出方式?研究质量方面,来自高校和非高校机构研究者之间的一些差异均有统计学意义?结论:为促进HTA研究结果的决策转化,建议确立促进HTA决策转化的支持机制,强化与决策方的沟通交流协作,提高转化认知水平,采用适宜且多样的研究结果产出方式?     

抽油机曲柄销的接触强度分析

计算了在极限弯矩作用下曲柄销紧固螺栓上的预紧力,根据各载荷的影响,利用理论计算的方法得到了曲柄销锥面上的应力分布情况.同时在有限元分析软件ANSYS中建立了抽油机曲柄销、锥套、曲柄体和螺母垫片、紧固螺母的实体装配模型,并在ANSYS软件中进行了接触分析,得到了各实体的应力分布情况.将两者对比分析,有限元计算的结果与理论力学模型计算结果相吻合.根据此结果对曲柄销的转动力矩进行了计算,分析了曲柄销出现转动的原因.     

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。     

制造系统生产单元碳排放核算模型

制造业是我国国民经济的支柱产业，但也是环境污染物排放的主要来源、能源消耗主体和温室气体排放大户。制造系统高能耗、高物耗、高碳排放的加工过程是造成制造业碳排放量大的重要原因。生产单元作为制造系统的加工的主体，其碳排放量的核算是确定整个制造系统乃至制造业碳排放总量的关键。本文首先对生产单元的原材料、电能、辅助物料及废屑处理所引起的碳排放进行分析，确定生产单元的碳排放源；其次，产品合格率的不同会造成生产单元输入及输出的成品/半成品数量的差异，进而影响生产单元单位产品的碳排放量，在此基础上，综合考虑了原材料、电能、辅助物料及废屑处理的碳排放情况，构建了给定工艺流程下生产单元碳排放核算模型。最后，结合一汽车排气装置加工实例，分别核算加工过程中九个生产单元的碳排放量，验证了模型的可行性。