A goal programming model for the siting of multilevel EMS systems.

Facility siting models known as location covering techniques have proven to be useful particularly for emergency medical services (EMS) planning, given the importance of ambulances responding to demand within some maximum time constraint. These models represent a set of methods which focus the health planner's attention on the access of people to health care, since they attempt to “cover” people in need of service within some specified time standard.This research develops a technique for the locational planning of sophisticated EMS systems, characterized by multiple levels of emergency health services. Specifically, a two-tiered system with “basic life support” and “advanced life support” capabilities is modeled as a goal program.By applying location covering techniques within a goal programming framework, this study develops a method for the siting of multilevel EMS systems so that (1) each service level maximizes coverage of its own demand population, and (2) “back-up” coordination between levels is assured. The usefulness of this goal program as a health planning tool is evidenced in the model's explicit articulation of EMS policy objectives and its ability to link system levels in terms of “goal-directed behavior”. The working of this multilevel covering model is demonstrated by reference to EMS planning scenarios and related numerical examples.     

Simulation modeling and optimization for ambulance allocation considering spatiotemporal stochastic demand

To ensure a timely response to emergencies, governments are obliged to implement effective ambulance allocation plans. In practice, an emergency medical service (EMS) system works in an uncertain environment, with stochastic demand, response-times, and travel-times. This uncertainty significantly affects ambulance allocation planning. However, few studies in this field adequately consider the effect of spatiotemporal uncertainty in demand, because it is difficult to measure it quantitatively. As a result, few analytic models capture the dynamic nature of an EMS system and, thus, the allocation plans they generate are not efficient in practice. Therefore, this study proposes a simulation-based optimization method for ambulance allocation. A simulation model is constructed to mimic the operational processes of an EMS system, and to evaluate the performance of an ambulance allocation plan in an uncertain environment. Gaussian mixture model clustering is used to derive the uncertain spatial demand. Then, the simulation generates emergency demand based on the obtained spatial distribution. A Gaussian-process-based search algorithm is used together with the simulation model to identify optimal solutions. To validate the proposed method, a case study is conducted using data on emergency patients in the Shanghai Songjiang District. Compared with the current plan adopted in Songjiang, the experimental results demonstrate that the delay time and frequency of the EMS system can be reduced significantly by employing the proposed methods. Furthermore, nearly 41% of the allocation cost can be saved.     

基于模糊聚类的最大树算法和重心法的区域航空中转站选址研究

首先,利用模糊聚类的最大树算法对城市进行分类,将快递企业的服务区域分成若干个子区域。其次,以运输成本最小为目标,利用重心法确定航空中转站所在的城市。最后,为提高该方法的适用性,进一步设计基于模糊聚类最大树算法的区域划分程序和基于重心法的中转站选址程序。     

A Kalman filter formulation for noisy regional job data

A problem of great concern to regional economic forecasters is how to know the current local economic status given the delays and noise in provisional data. In this paper the structure of revisions to one of the most important regional data sets, local jobs by industry, is analyzed. A Kalman filter formulation is presented that can be used to improve the monthly estimates of jobs in local industries where large subsequent data revisions are most likely. Two data sets, one for the State of Virginia and one for the Louisville MSA, are used to illustrate the technique. The results, while not conclusive, suggest that the technique may be of practical importance in the monitoring and forecasting of employment activity in mining, construction and other industries for which provisional estimates are subject to the greatest later revision.     

Sectoral Shocks and Metropolitan Employment Growth

In this paper, we study the sources of industry employment growth in each of five metropolitan statistical areas (MSAs). The objective is to understand the relative importance of aggregate disturbances versus local sectoral shocks in generating observed employment fluctuations at the MSA level. The empirical evidence presented in this paper derives from structural vector autoregressions (SVARs), estimated for each of the five MSAs. Estimations use monthly employment data covering nine one-digit industrial categories for the period 1951:1–1999:8, as well as two variables that capture the influences of aggregate (i.e., national) shocks on MSAs. We find that within-MSA industry shocks explain considerably more of the forecast error variance in industry employment growth than do aggregate shocks. Sectoral shocks account for between 87 and 94% of the 36-month-ahead forecast error variance. Among individual local sectors, shocks to MSA-specific government, manufacturing, and service sector employment growth are the predominate sources of variability.     

The effects of mergers on price and output: Two case studies from the airline industry

The literature on industrial organization contains very little direct evidence on the effects of actual mergers. This study estimates the effects of two recent airline mergers approved by the Department of Transportation over the objection of the Department of Justice. The merger of TWA and Ozark appears to have caused a slight increase in fares and a far greater reduction in service on city pairs out of St Louis. The merger of Northwest and Republic appears to have caused a significant increase in fares and a significant reduction in overall service on city pairs out of Minneapolis-St Paul.     

住房与交通综合可支付性指数的设计与应用——以北京为例

城市空间结构的理论及实证研究表明,城市土地利用与交通系统之间存在着密切的互动关系.在空间上,居民所负担的住房成本和交通成本通常呈现此消彼长的关系.因此,单纯考虑"住房成本占收入的比重"不能全面衡量居住区位选择所引致的成本.为了更全面和精细地评价居民对于住房成本和交通成本的综合支付能力及其空间分布特征,设计了住房与交通综...     

带多重机率约束的售后服务设施选址模型研究

将服务效益最大化及利益最公平作为目标,考虑了费用约束,建立售后服务设施选址模型,对模型的复杂性进行了讨论,并给出了算法设计和算例。     

配送中心选址问题研究文献综述

通过研究、分析、归纳和总结国内外配遥中心选址问题研究文献,提出新的分类法。即单独研究配送中·心选址问题类和结合物流管理的库存战略、运输战略、顾客服务目标等其它战略研究配送中心选址问题类。根据列举、剖析两类文献中的典型文献和分析物流配送业的新趋势、新发展,提出配这中心选址问题研究的新方向——基于顾客满意度的多目标配送中心选址问题。     

Assessing geographic coverage of the essential air service program

Essential air service (EAS) is a federally funded program that helps provide commercial air transport service from smaller, geographically remote communities in the United States. While critics of this program frequently cite the underutilization of EAS connections as being an indicator of wasteful public spending, recent studies suggest that the spatial configuration of EAS subsidized airports may also contribute to systemic inefficiencies. The purpose of this paper is to explore the prospects for reducing EAS allocations while meeting existing geographic service needs. The analysis of this public sector service is structured using classic location coverage problems to examine whether there are any system inefficiencies. This enables an objective assessment to be carried out, using spatial optimization modeling approaches. The subsequent analysis provides the basis for a number of public policy insights, including the evaluation of service redundancies, the impact of geographic proximity guidelines and the potential for expanding coverage of the EAS program.     

Robust stochastic frontier analysis: a Student’s t-half normal model with application to highway maintenance costs in England

The presence of outliers in the data has implications for stochastic frontier analysis, and indeed any performance analysis methodology, because they may lead to imprecise parameter estimates and, crucially, lead to an exaggerated spread of efficiency predictions. In this paper we replace the normal distribution for the noise term in the standard stochastic frontier model with a Student’s t distribution, which generalises the normal distribution by adding a shape parameter governing the degree of kurtosis. This has the advantages of introducing flexibility in the heaviness of the tails, which can be determined by the data, as well as containing the normal distribution as a limiting case, and we outline how to test against the standard model. Monte Carlo simulation results for the maximum simulated likelihood estimator confirm that the model recovers appropriate frontier and distributional parameter estimates under various values of the true shape parameter. The simulation results also indicate the influence of a phenomenon we term ‘wrong kurtosis’ in the case of small samples, which is analogous to the issue of ‘wrong skewness’ previously identified in the literature. We apply a Student’s t-half normal cost frontier to data for highways authorities in England, and this formulation is found to be preferred by statistical testing to the comparator normal-half normal cost frontier model. The model yields a significantly narrower range of efficiency predictions, which are non-monotonic at the tails of the residual distribution.

     

A reformulation of the aggregate planning problem

This article proposes a reformulation of the aggregate planning problem which more closely agrees with situations frequently encountered in practice. The proposed reformulation assumes that a firm's production planners want to determine the expected service and inventory levels for a given production profile in the face of uncertain seasonal demand. By using several different production profiles that are each consistent with the firm's staffing, subcontracting, and overtime policies, it is possible to pick the profile that best meets the firm's preferences for service level and inventory turns. Actually, the trade-offs between inventory and service levels are examined so that an informed choice can be made by all of those concerned.One of the advantages of the proposed model is that communications can be established among production, marketing, and finance managers who often have conflicting goals. Also, levels for inventory turns, service, and production can be set that are consistent with each other. Furthermore, several alternative production profiles can be examined in a relatively short time through the use of the simulation model proposed.An application of the model to the Wagner Spray Tech Company, a producer of painting equipment, is presented. In this particular case, where forecasting errors are quite high, some of the potential uses of the model are presented. Also, reasons are given why this particular reformulation of the aggregate planning problem was found to be useful.     

客运专线行包运输体制研究

本文在全面分析铁路行包运输特点的基础上,提出了基于客运专线的三种可行的行包服务模式,通过深入分析其各自优缺点,整合出较适应我国客运专线行包运输的服务模式。最后对行包运输中的大件行包运输方式及其市场运营模式进行了探讨。     

Multiple equilibria in two-sector monetary economies: An interplay between preferences and the timing for money

In this paper, we study the occurrence of local indeterminacy in two-sector monetary economies. We consider a general MIUF model with two alternative timings in monetary payments: the Cash-In-Advance timing, in which the cash available to buy goods is money in the consumers’ hands after they leave the bond market but before they enter the goods market, and the Cash-After-the-Market timing, in which agents hold money for transactions after leaving the goods market. We consider three standard specifications of preferences: the additively separable formulation, the Greenwood–Hercovitz–Huffman (GHH) (Greenwood et al., 1988) formulation and the King–Plosser–Rebelo (KPR) (King et al., 1988) formulation. First, we show that for all the three types of preferences, local indeterminacy occurs under the CIA timing with a low enough interest rate elasticity of money demand. Second, we show that with the CAM timing, although determinacy always holds under separable preferences, local indeterminacy can occur with GHH and KPR preferences. We thus prove that compared to aggregate models, two-sector models provide new rooms for local indeterminacy when non-separable standard preferences are considered.     

Causality reconsidered: A note

This note extends the recent work of Steinnes by formulating and testing a similar but more complete dynamic reduced form model of intraurban location decisions. The formulation of the model corrects a specification error by Steinnes, and a dummy variable technique is applied to yield consistent estimates. The results include relations between the employment sectors as well as between population and employment and, when they differ from those previously published, they are more plausible. The basic conclusion of the note is that “jobs follow people.”     

地方公共养老服务体系建设水平及其影响因素研究

以我国31个省区市2011—2016年的面板数据为基础，对其进行熵值法处理，并采用广义最小二乘法进行模型异方差和自相关修正，对地方公共养老服务体系建设水平进行研究，得出以下结论：一地土地成交价格越高、纳入城乡最低保障范围内人数越多、老年抚养比越高等，越不利于地方养老服务体系建设水平提升；中央专项拨款、福利彩票公益金提取越多，则越有利于地方政府对养老服务体系建设水平的提升。根据所得结论对地方公共养老服务体系的建设提出包括稳定地价、制定土地优惠政策以及进行前期建设补贴在内的相关建议。     

A healthcare facility location problem for a multi-disease,multi-service environment under risk aversion

This paper presents a stochastic optimisation model for locating walk-in clinics for mobile populations in a network. The walk-in clinics ensure a continuum of care for the mobile population across the network by offering a perpetuation of services along the transportation lines, and also establishing referral systems to local healthcare facilities. The continuum of care requirements for different diseases is modelled using coverage definitions that are designed specifically to reflect the adherence protocols for services for different diseases. The risk of not providing the required care under different realisations of health service demand is considered. In this paper, for a multi-disease, multi-service environment, we propose a model to determine the location of roadside walk-in clinics and their assigned services. The objective is to maximise the total expected weighted coverage of the network subject to a Conditional-Value-at-Risk (CVaR) measure. This paper presents developed coverage definitions, the optimisation model and the computational study carried out on a real-life case in Africa.     

New Keynesian monopolistic competition and objective demand

The New Keynesian model of monopolistic competition by Blanchard [Blanchard, O., Kiyotaki, N., 1987. Monopolistic competition and the effects of aggregate demand. American Economic Review 77 (4), 647–666] is reformulated according to an objective demand approach making the behavior of all agents fully rational. The revised model is compared with the original model in terms of prices, quantities and welfare. Working with the revised model enhances the validity of the menu-cost argument and, different from the original model, implies that price rigidity is increasing in market concentration.     

中邮速递（EMS）的发展战略分析

近年来电子商务的发展速度高达200％-300％，但作为其下游产业的物流业发展速度却仅有40％左右，物流服务远远跟不上电子商务的发展。马云说：“未来十年是物流时代”。而作为快递业龙头老大的EMS自然成为万众瞩目的焦点。文中借助波特模型和SWOT分析法对EMS的市场现状和自身能力进行深刻的剖析，找出EMS发展的内部优劣势和外部环境机会与威胁，进而探索出一条适合EMS未来成长的发展道路。