Some spatial equilibria in facility investment under uncertain demand

This paper describes the spatial distribution of customer demand, supply of customer services and facility investment, as the outcome of a three-level game-like interaction between customers (e.g., shoppers), suppliers (e.g., retailers) and developers (e.g., landlords). Treating both the suppliers and developers at each centre as competitors, oligopolistic equilibria of the Nash-Stackelberg type are developed, and conditions for their existence and uniqueness established. Uncertain customer demand is specified in probabilistic terms, representing the suppliers' perception of expected customer behaviour.     

Construction spatial modeling and scheduling with three-dimensional singularity functions

Previous approaches for construction project scheduling have been limited to one dimension of time for bar charts and two dimensions for linear and repetitive scheduling approaches, which added a measure of work quantity. The question therefore arises if and how it is possible to derive a three-dimensional and ultimately multi-dimensional model. Reviewing mathematical theory finds that traditional functions lack the capability to express intervals for activities. Singularity functions are therefore chosen to newly derive stationary and directional activities in a Cartesian coordinate system, wherein the two dimensions of the floor plan area plus one dimension of time are explicitly modeled in an integrated manner. They are implemented into a conflict-avoiding heuristic scheduling algorithm that minimizes total project duration, which is computerized and validated with example calculations.     

Price variation in spatial markets: the case of perfectly inelastic demand

This paper analyzes short-run price variation in one-dimensional (i.e., circular, linear) spatial markets where both producers and consumers are numerous. Price reaction functions are established for firms under symmetrical price conjectures. For perfectly inelastic consumer demand each firm's equilibrium price is shown to depend upon distance-decay effects in both firms' locations and marginal costs. The rate of distance decay in these effects is inversely related to the degree of price conjectural variation in the market. Boundary effects in spatial markets are also shown to influence these distance-decay rates and, thus, patterns of firms' equilibrium prices.An earlier version of this paper was presented at the IGU Mathematical Models Working Group in Canberra, Australia during August 1988. The authors gratefully acknowledge the comments of two referees     

Consumer demand,conjectural interdependence,and location equilibria in simple spatial duopoly

Papers in Regional Science -     

Accurate water demand spatial allocation for water networks modelling using a new approach

The paper presents an alternative approach regarding the spatial allocation of the actual water demand (at node level) when developing a pipe network's hydraulic simulation model. The process takes into account the respective demand patterns of the various types of water users, considering the water being lost through leaks/breaks occurring, as a competitive use. This new method accurately approximates the demand allocation of a network when there is no GIS data, thus having a significant impact on its cost effectiveness. Kos Town (Greece) water pipe network is used as the case study to demonstrate the entire process and the problems encountered. Finally, to prove its effectiveness the results of the new method were compared to MW-Voronoi diagram method's results and to field measurements.     

Generation of synthetic water demand time series at different temporal and spatial aggregation levels

This paper presents a procedure for the generation and spatial-temporal aggregation of synthetic water demand time series which reproduce the main statistics - mean, variance and (spatial and temporal) covariance - of the corresponding observed series. Starting from observed historical time series taken at low levels of temporal aggregation (e.g., one minute) and relating to individual users, the procedure enables a) the generation of synthetic water demand time series for every individual user with a time step of one minute, b) the temporal aggregation of these synthetic series in order to obtain synthetic water demand time series with a time step, for example, of one hour, and which are such as to reproduce the hourly mean, variance and temporal covariances of the corresponding temporally aggregated historical time series, and c) the spatial aggregation of the synthetic hourly water demand time series of every user in order to generate a synthetic water demand time series that is representative of the entire group of users considered, and is such as to reproduce the mean, variance and temporal covariance observed at that level of spatial aggregation; The entire procedure was parameterized and applied to a case study on the water demands of 21 users of the water distribution system of Milford (Ohio). The results obtained show that the temporal aggregation procedure is effective in generating hourly water demand time series that preserve the mean, variance and temporal correlation of the historical time series for every individual user, while the spatial aggregation method shows good level of effectiveness in preserving the statistics of the aggregated series. Overall, the proposed procedure is demonstrated to be a valid tool for the bottom-up generation of synthetic water demand time series at various levels of spatial-temporal aggregation which reproduce the mean, variance and covariance statistics of the historical time series.     

A note on “Price variation in spatial markets: the case of perfectly inelastic demand”

Summary These considerations are based on the need for consistent models. If we look at the spatial oligopoly approach of Mulligan and Fik from this point of view, we draw two conclusions. First, their model does not indicate any reasons for asymmetrical conjectural or actual price reactions in the market, as they are not influenced by any different marginal production costs and different locational distributions. Second, exactly one conjectural reaction coefficient is consistent with the profit-maximizing behavior of the firms, and this coefficient is identical for all firms in the market. Consequently, the alternative market results for different reaction coefficients in the paper of Mulligan and Fik are reduced toone result atconsistent conjectural reaction coefficients.     

关于离散分布参数的区间估计

关于（０ —１） 分布参数Ｐ的区间估计,可利用中心极限定理,近似于Ｎ（０ ,１） 分布的方法导出．本文用随机变量概率分布的方法导出了ｐ 的另一种区间估计,并用此方法导出了π（ λ） 分布的参数λ的区间估计．     

Dispersed water-containing composites based on hydrophobic materials

Disperse water-containing composites based on hydrophobic materials and containing up to 90 percent by weight (wt %) of water have been obtained. It is shown that the water-retaining capacity of these composites can be controlled by introducing hydrophobic graphite into their composition.     

Point-to-point migration functions and gravity model renormalization: approaches to aggregation in spatial interaction modeling

Two distinct approaches to assessing the effect of geographic scale on spatial interactions are modeled. In the first, the question of whether a distance deterrence function, which explains interactions for one system of zones, can also succeed on a more aggregate scale, is examined. Only the two-parameter function for which it is found that distances between macrozones are weighted averaged of distances between component zones is satisfactory in this regard. Estimation of continuous (point-to-point) functions--in the form of quadrivariate cubic polynomials--for US interstate migration streams, is then undertaken. Upon numerical integration, these higher order surfaces yield predictions of interzonal and intrazonal movements at any scale of interest. Test of spatial stationarity, isotropy, and symmetry of interstate migration are conducted in this framework.     

Assessing the applicability of global CFC and SF(6) input functions to groundwater dating in the UK

Chlorofluorocarbons (CFCs) and sulphur hexafluoride (SF(6)) are increasingly being used to date recent groundwater components. While these trace gases are generally well-mixed in the atmosphere, there is evidence that local atmospheric excesses (LAEs) exist in some areas of the world, primarily associated with urbanisation and thereby affecting the interpretation of data derived from groundwater studies. Since the soil acts as a low-pass filter for atmospheric trace gas fluctuations, the possible existence of LAEs in the UK has been investigated by measuring the mixing ratios of CFC-11, CFC-12 and SF(6) in soil gases from sites within the UK's two largest cities (London and Birmingham) and a smaller urban area, Bristol. While there was some evidence of excesses, most of the measured mixing ratios for CFC-12 and SF(6) were less than 10% above the current northern hemisphere atmospheric mixing ratio (NH-AMR) values. CFC-11 was more variable, but usually less than 20% above the NH-AMR value. Surface waters were also investigated as possible short-term archives of trace-gas information but were much less consistent in performance. While the lack of significant current LAEs for SF(6) can justifiably be extrapolated to past decades, different global emission patterns mean that this is much harder to justify for the CFCs. Nevertheless, in the absence of further evidence it is concluded that the use of CFC and SF(6) input functions based on the NH-AMR curves is generally justified for the UK, with the proviso that urban groundwater investigations should not rely on the CFCs as age tracers.     

德国机械产品的全球需求

不论是在加拿大一望无垠的荒野中治理沙漠.或是在阿联酋建造如迪拜塔那样的高塔,不论是气贯长虹的三峡大坝工程,还是瑞士圣哥达铁路隧道工程(GBT),"德国制造"的建筑设备及建材机械都已在全球广泛使用!同时,世界对于机械、人员和材料的要求也在不断增长.在这三个方面既要具备耐久性,还要有各种施工条件下的稳定性能和表现--高温、高寒地区、海拔5000m的高地、人口密集之地以及不适宜人类居住之地,例如沙漠或海底.世界对德国建筑机械技术的需求较以往更高.纵观2007年.德国建筑设备及建材机械制造商的总销售额为152.6亿欧元.     

拉力分散型预应力混凝土抗拔桩设计

多层或低层裙房的地下室埋置深度较深,或地下车库无地上房屋及顶板上覆土较少,当地下水位埋藏较浅时,建筑地下室存在上浮问题。根据桩身轴力沿桩长的分布规律和预应力技术分析,论证了采用拉力分散型预应力抗拔桩抵抗水浮力的可行性,并提出拉力分散型预应力抗拔桩的设计方法。与传统的普通抗拔桩相比,在不增加工程成本前提下,作为永久性抗浮措施技术性更加合理,具有特别重要的工程实用意义。     

离散数据的连续函数拟合问题

基于回归分析方法,借助于计算机,探讨了社会经济管理和工程技术系统中的离散数据的连续函数拟合问题,并且提出了对实测数据建立单变量多种多项式函数的系统设计思路和程序。     

Conservation of Water in Gel and Dispersed Structurally Stable Composites

Obtained are gel (from sodium carboxymethyl cellulose, bentonite and water) and dispersed (from fumed silica, graphite and water) water-contained composites, which include up to 90% of water. Quality of water in composites meets the requirements for drinking water and is determined by the technology of their production. It is shown that water-retaining capacity of water-containing composites depends on the composition and structural-mechanical characteristics.     

Estimation of transportation demand

Conclusion The present analysis of transport demand for manufactured iron and steel products, one of the high-valued commodities, results in price elasticities of demand which are midly elastic with regard to motor carriers and slightly inelastic with regard to railroads. These estimates are sufficiently at variance with the elasticity findings for all manufactured goods together to suggest that there probably exists a rather broad spectrum of transport demand elasticities for most manufactured goods.²² Together with the elasticity estimates obtained, motor carriers have been capturing larger shares of the transport service market over time, more so than would be expected from the price elasticities alone. This is to suggest that nonprice determinants may be crucial in transport desision making, even in the short run.Railroads derive disproportionately large revenue contributions from manufactured goods. Were they to engage in a pricing policy which approximated marginal costs it appears that the rapid growth in the motor carrier share of the manufactured goods market might be halted. Such a pricing policy would not only shift intermodal competition as to commodities handled, but more importantly, it would reintroduce intermodal competition by lengths of haul. Perhaps comparative advantage, and thereby optimal allocation, would be enhanced.     

需求侧管理综述

介绍了需求侧管理（DSM）的发展及实施咧的意义，阐述了以经济激励为主的负荷管理方案及DSM中的节电技术，提出了DSM实施中的注意事项，为深入开展需求侧管理做准备。