Incorporating a tracking signal into a state space model

It is a common practice to complement a forecasting method such as simple exponential smoothing with a monitoring scheme to detect those situations where forecasts have failed to adapt to structural change. It will be suggested in this paper that the equations for simple exponential smoothing can be augmented by a common monitoring statistic to provide a method that automatically adapts to structural change without human intervention. The resulting method, which turns out to be a restricted form of damped trend corrected exponential smoothing, is compared with related methods on the annual data from the M3 competition. It is shown to be better than simple exponential smoothing and more consistent than traditional damped trend exponential smoothing.     

Open space, residential property values, and spatial context

We use hedonic analysis of home transaction data from the Minneapolis–St. Paul metropolitan area to estimate the effects of proximity to open space on sales price. We allow the effects of proximity to vary with demographic and location-specific characteristics and include fixed effects to control for observed and unobserved neighborhood characteristics. We find that the value of proximity to open space is higher in neighborhoods that are dense, near the central business district, high-income, high-crime, or home to many children. Using the metropolitan area's average value may substantially overestimate or underestimate the value of open space in particular neighborhoods.     

浅谈城市地下空间火灾预防与管理

城市地下空间由于其特殊的构造,发生灾害时遭受的损失更为严重。文章主要从地下空间火灾发生机理入手,阐述了地下空间火灾特征,论述了如何做好地下空间火灾的预防和灾害管理。     

Incorporating morale into a classical agency model: implications for incentives, effort, and organization

This paper incorporates morale into a standard principal-agent model. When morale is observable, the worker’s effort level, the optimal piece rate, and the firm’s expected profits are all generally increasing in the worker’s level of morale. Furthermore, under reasonable conditions, higher-morale individuals are more responsive to incentives. Finally, when considering morale interdependence, conditions are derived which determine optimal organization strategies in terms of pooling or separating workers, and corresponding staffing policies are discussed.      

城市居住空间的符号分化与身份建构——以南京市东山区为个案

当前我国城市居住空间的符号分化趋势日益明显,不同档次居住空间的符号生成机制存在差异,而符号分化的居住空间将对居住群体的社会身份产生建构作用。本文在实证调研的基础上对这些问题加以描述和分析。     

Integrating expected coverage and local reliability for emergency medical services location problems

Daskin's MEXCLP model [Daskin M. A maximum expected covering location model: formulation, properties, and heuristic solution. Transportation Science 1983;17:48-70] was one of the first efforts to capture the stochastic nature of emergency medical services (EMS) location problems within a mixed-integer formulation. With their subsequent introduction of MALP, ReVelle and Hogan [The maximum availability location problem. Transportation Science 1989;23:192-200] offered two key advances, local vehicle busyness estimates and the α-reliability objective. While these constructs have influenced many subsequent EMS location models, they have been subjected to relatively little empirical analysis. To address this, we introduce the LR-MEXCLP, a hybrid model combining the local busyness estimates of MALP with the maximum coverage objective of MEXCLP. We then solve a series of problems with all three models and employ simulation to estimate aggregate service levels. We find that LR-MEXCLP leads to modest but consistent service gains over both MALP and MEXCLP. These results support the merits of local busyness estimates, but they also suggest that the α-reliability objective may be inappropriate when seeking to maximize aggregate system response capabilities. More generally, our research underscores the utility of (a) linking modeling assumptions and goals with real-world application contexts, and (b) employing simulation or other techniques to validate theoretical results.