Spatial pricing, optimal location and social welfare with consumer arbitrage

This paper provides a comprehensive comparison of the optimal location, output and welfare of spatial discriminatory pricing by integrating consumer arbitrage into the Hwang and Mai (Am Econ Rev 80:567–575, 1990) model. It shows that the presence of arbitrage creates a significant influence on a firm’s locational choice and thus generates different welfare implications. When the discrepancy between the two markets is small, the optimal location and the resulting social welfare level under discriminatory pricing and mill pricing policies remain the same; however, when the discrepancy between the two markets is large, the two pricing policies yield different optimal locations which make the welfare under discriminatory pricing higher than that under mill pricing, hence reversing the support for anti-trust legislation.     

Finding the optimal positioning of exits to minimise egress time: A study case using a square room with one or two exits of equal size

In this paper, we use an egress computational simulation model to determine the optimal positioning of exits around the perimeter of a square room in order to minimise egress times. The solution is found through trial and error exploration of the possible significant exit locations. The egress simulations were conducted assuming idealised conditions of zero response times and population behaviour such that occupants elect to move towards their nearest exit. The analysis reveals that strategic positioning of even a single exit on the perimeter of the room can result in reduced egress times. Even greater advantage can be gained by the strategic positioning of two exits of equal size. It was also noted that the advantage offered by the identified optimal locations diminishes as the size of the exit increases while keeping the population serviced by the exits constant, or the size of the population serviced by the exit decreases while keeping the size of the exits constant.     

农村“三合一”门店和“三合一”加工作坊消防安全治理整顿之我见

对农村“三合一”门店和“三合一”加工作坊消防安全现状进行了分析，提出了解决问题的办法。     

The location of governmental facilities and equilibrium urban configuration

Most existing models of spatial agglomeration economics do not include the effects of the governmental sector in an urban configuration, although the governmental sector plays an important role in economic activity. We discuss how an exogenous distribution of locations of governmental facilities and the level of service provided affect the equilibrium urban configuration under the assumption that governmental service is necessary component for production of goods by a firm. The model yields multiple equilibrium urban configurations endogenously, depending on the set of parameters, and that the governmental sector is responsible for the movement of equilibrium market land rents stemming from its determination of location.Comments and suggestions by anonymous referees are gratefully acknowledged. A preliminary draft of this paper was presented at The Second Summer Institute of the Pacific Regional Science Organization, held on July 20–23, 1992, in Taipei, Taiwan, R.O.C. I thank to M. Fujita and H. Koide for helpful comments and suggestions.     

The effect of internal heat source and opening locations on environmental natural ventilation

Two-dimensional computational simulations are performed to examine the effect of open location on natural ventilation for room with an internal heat source. The room is symmetrically cooled from the sides and insulated from lower and upper walls. The analysis of the fluid flow and heat transfer characteristics of the natural ventilation was carried out by the method of streamline and temperature contours. Three different cases of local open length on lower and upper walls are studied for Rayleigh numbers ranging from 10³ to 10⁵ and open aspect ratio varied from 0.0 to 0.8. The results show that the enhancement of the heat transfer is the greatest at high Rayleigh numbers and open aspect ratios. The best position for the open locations was found out to be on the upper wall as shown in case 3.     

简易自动喷水灭火系统在中小型场所中的应用

通过中小型场所的火灾实体模拟试验,说明了在中小型场所中设置简易自动喷水灭火系统的可行性和重要性。     

路票约束下的用户均衡网络流建模及其算法

为了缓解交通拥堵问题,在传统用户均衡模型的基础上,建立了带路票约束条件的用户均衡网络模型。本模型采用牛顿算法作为子算法,结合增强拉格朗日乘子法求解带路票约束的用户均衡网络流。外惩罚函数通过调整惩罚参数,把容量约束下的网络均衡问题转化成传统网络均衡问题。牛顿法通过移动方向、修正矩阵和移动步长的组合来保证路径或路段交通流量解的可行性,同时获得转化后子问题的最优解。算例分析表明,相对于传统的交通分配方法,添加路票约束能显著改变交通分配结果,使高流量路段的交通量减少了25%,能够有效地缓解交通拥堵。     

单、双热源置换通风系统流场及温度场的数值模拟

利用计算流体力学(CFD)方法,分别对单、双热源置换通风系统进行了数值模拟。分析和比较了两种情况下室内空气的速度和温度分布,指出室内温度场在垂直方向上存在三个温升层;单、双热源形成的垂直温度分布有较大差别;双热源送风参数的计算不能简单按单热源的计算参数进行,应考虑热源分散的影响。     

盖梁施工夹箍支撑技术的探索与应用

分析了夹箍支撑这种盖梁施工新的支撑方式的工作原理,通过在沈长公路老岭隧道段S02标段的实际应用,结合基本力学知识着重分析了它的工作原理和受力状况,并对其应用效果作了详细阐述。     

钢储罐基础环墙的设计与实践

结合笔者在钢储罐环墙式钢筋混凝土基础方面的工程实践,以及对中国石化总公司行业标准SH3068-95《石油化工企业钢储罐地基与基础设计规范》的理解,着重介绍钢储罐环墙式钢筋混凝土基础工程实践中应注意的几个问题及设计计算所采用的方法。     

边坡各种极限平衡条分法对比分析

对条分法作了简单概述,就基于不同假设条件下的各种极限平衡条分法进行了对比分析,同时对各种条分法的计算精度作了分析,最后总结出极限平衡条分法的局限性,以期为边坡的稳定性分析奠定基础。     

The use of DOE-2 to determine the relative energy performance of daylighted retail stores covered with tension supported fabric roofs

With increasing interest amongst the architectural and engineering community in daylighted buildings, there is a need to evaluate the relative energy performance of those buildings. One means of daylighting a building is to use a coated glass fiber fabric roof. With such a roof, it has been found that sufficient daylight is admitted to allow most artificial lighting to be turned off during the daytime hours. However, solar cooling loads and conductive loads may be greater than for conventionally roofed commercial buildings. With the fabric roofed buildings capable of using considerably less energy for artificial lighting, yet possibly requiring greater use of energy for space heating and cooling, the relative energy performance is a matter of trade-offs.To determine this relative energy performance of fabric roofed and conventionally roofed retail stores, a modified version of DOE-2.1A was used with weather data from 19 cities located within the United States. In the analyses, both single-layer and double-layer roofs were studied as were stores with different levels of electric power for artificial lighting. In general, the results suggest that a fabric roofed store will use less total energy than a conventional roofed store in a geographic area with a mild climate but that it will use more energy in a cold climate area.     

苏州园林中的“有”“无”与现代建筑

从"有"与"无"这看似具有佛教意味的一对矛盾体入手,探讨其在苏州园林中的存在符号包括山石、空间和精神等,并且对其在现代设计中的延伸作了初步的研究和展望,从而使中国文化向更深层次的方向发扬壮大.     

The equilibrium of attached and unattached radon daughters in the domestic environment

The Jacobi Room Model is applied to fit radon daughter concentrations measured in a room. The aerosol size distribution and ventilation rate are measured simultaneously. The mean deposition rate fitted to these experiments is 16 h^?1. Once all parameters are fixed, the unattached fraction and the effective dose equivalent are calculated, and are put in perspective to the Working Level concept.     

盾构双隧道不同开挖顺序及不同布置形式对管线的影响研究

在离心模型试验中同时考虑隧道开挖所致地层损失效应和质量损失效应,研究不同开挖顺序及不同布置形式下双隧道开挖对管线的影响规律。同时采用基于地层损失比的位移控制有限单元法对离心模型试验及其他4组拓展工况进行分析,其中土体本构模型采用考虑土体小应变特性的HP(Hypoplasticity model)模型,并将试验结果与已有的解析方法进行对比。研究结果表明,双隧道不同开挖顺序及不同布置形式对地表沉降、管线沉降、管线弯曲应变的影响显著;管线存在所产生的"遮拦"效应对管线正上方地表沉降的影响程度随着自由场最大地表沉降的增加而逐渐加剧;双隧道开挖所致管线沉降的主要影响区域为-1.2D_T~1.2D_T;实际工程中应加强浅埋后继隧道开挖时管线工作性状的监测工作,且不应简单采用叠加原理对不同施工工序及不同布置形式的双隧道开挖所致地表沉降、管线沉降及管线弯曲应变进行预测,应合理考虑后继隧道开挖所致土体的累计剪切应变及上覆隧道的遮拦效应对管–土相对刚度的影响。     

地震埋压现场人员的搜索和救援

介绍了地震埋压现场人员的搜索定位和营救技术,指出了搜救工作中应该注意的问题.     

边坡锚固优化设计理论与应用

论述了边坡锚固优化设计的概念、原理及方法，并运用该理论对牛矿东山头滑体的加固设计进行了实例分析。