Hub facility location with fixed costs

In thep-hub location model, it is usual to ignore the fixed costs of opening facilities. In contrast, the simple plant location problem includes fixed facility costs and thereby makes thenumber of facilities one of the decision variables. This paper introduces fixed facility costs into a hub location model, thereby making the number of hubs a decision variable. As an initial effort toward solving the hub model with fixed costs, a two-step procedure is devised.Step 1 involves an estimate of a good upper bound on the solution, using heuristics.Step 2 involves the computation of a tight lower bound on the solution; as a by-product, an improvement of the best solution from Step 1 may be found. Computational results are discussed for sample problems.An earlier version of this paper was presented at the 35th North American Meetings, Toronto, November 1988.     

Simplifying the normalizing factor in spatial autoregressions for irregular lattices

The Jacobian term appears in certain likelihood functions as a normalizing factor; it ensures that the use of variable transformations still leads to probability density functions whose complete integration yields unity. This term is particularly troublesome when dealing with spatial autoregressive models in that it requires numerically intensive solutions to accompanying parameter estimation problems. For these types of autoregressive models, the Jacobian term is a function of the eigenvalues of then-by-n connectivity matrix that depicts the geographic configuration of the areal units under study. This paper reports on Jacobian approximation results, based upon supercomputer and other experiments, for irregular lattices.An earlier version of this paper was presented to the 37th annual North American Meeting of the Regional Science Association, Boston, November 9–11, 1990.     

Planning for spatial equity in Europe

Since planners plan, they claim that their local, regional or national spatial plans are crucial for achieving spatial equity. Starting from the difficulties of defining spatial equity, the paper explores some European dimensions of spatial equity, thereby referring to three recent documents: the Commission's First Report on Social and Economic Cohesion, the Opinion on Spatial Planning of the Committee of the Regions and the draft European Spatial Development Perspective, having been approved by the Ministers of the Member States of the European Union in June 1997. This is followed by a brief assessment of the role of existing European networks of infrastructure, production, information and power, or those of memories and images, in creating spatial equity in Europe. The paper ends with a presentation and brief justification of the normative concept of the European Bunch of Grapes as a mental vision for spatial equity in Europe.     

Evaluating firefighting foams for aviation fire protection

The proliferation of performance guidelines and specifications for firefighting foams has created divergent opinions on aviation fire protection standards. In this paper the technical basis for current U.S. and international aviation guidelines is presented. Issues associated with small- and large-scale fire tests are discussed. The correlation between fire test methods in theU.S. Military Specification for aqueous film-forming foam (AFFF) and current aviation fire protection guidelines is established. Trends and areas for further development are outlined.     

Spatial search and spatial competition: a probability analysis of basic results from the spatially-restricted theory

Existing analyses of the interactions between spatial search and spatial competition are limited since it has been difficult to incorporate the complex routing component of the behavior. This paper examines the interactions between spatial search behavior and spatial competition using a probabilistic modeling strategy that doesnot restrict routing. Experimental analyses examine basic hypotheses from optimal search theory and competitive location theory in the context of spatial search. While experimental results support several of these basic hypotheses, the experiments also generate some contradictions and additional insights.     

The generation and disposal of solid wastes in Australia

In Australia there has been an increasing consumption of such materials as plastics, paper and metals which ultimately form solid wastes. It is expected that within the next 30 years the per capitasolid waste production, now 1#lb75 lbs/person/day, will double. This has led to a number of factors causing environmental problems. Attention is focussed on pollution, resource depletion and possible alternative resource usage, some of the problems which occur directly as a result of the consumption of a natural resource. In addition the problems caused by the production of waste containers, paper and such are discussed. These include garbage disposal and litter control in an urban society. Recycling of glass and paper products is now widely practised in Australia and plans have been made to recycle metal containers. In addition, some of the social issues pertinent to these topics are briefly outlined.     

A computer-vision-based and fuzzy-logic-aided security and fire-detection system

The paper starts with the introduction of the basic requirements of classical intrusion detection and alarm systems, and fire detection systems. The drawbacks of such conventional systems are highlighted. Techniques of computer vision are employed to remove the drawbacks and at the same time, increase the reliability and response rate of the systems. For security and low-level fire detection, a fuzzy-logic-based image-comparison algorithm is deemed adequate. In order to confirm the existence of fire or smoke, techniques related to optical flow are employed as high-level fire or smoke detection which generate a velocity field for the image so that the decision can be judged using fuzzy logic. Details of implementation and some experimental results have been included in the paper for illustration. This paper is reprinted from the Architectural Science Review,Volume 7, Number 1, pages 9–16.     

Section 94 developer contributions and marginal cost pricing

Abstract Developer contributions for infrastructure are a major feature of the development scene in New South Wales. They are enabled under s. 94 of the Environmental Planning and Assessment Act 1979. The second edition of the Section 94 Contributions Plans Revised Manual has now been in operation for three years. Although it incorporates important additional material compared to the first edition, it still does not address the problem of the efficient pricing of infrastructure through properly calculated s. 94 developer contributions. This paper sets out the case for using marginal cost pricing to determine the magnitude of developer contributions. It argues that the efficient pricing of local government service infrastructure should be viewed as part of the larger process of microeconomic reform in local government.     

Regional allocation of public investment

Conclusion In the previous Sections, we have observed the following interesting properties of the optimum solution to this regional allocation problem.First, as indicated by assumptions (33) (34), and (35), public investment in one of the regions will be justified during some phase of the planning period, even if it is less productive than the private investment in the same region. The reason is that the central government can directly control the interregional flow of public fundsoutside the market mechanism and can concentrate its public investment on the region with greater growth potential.Second, as seen by equation (41), the value of (T–t ^*), the length of the second phase of planning, is independent from the length of planning horizonT provided thatT>T–t ^*. Then, the relative significance of the second phase will be less and less asT becomes larger and larger. This is one of the characteristics which have been observed in the dynamic programming problems with linear form. Therefore, ifT is very large, the public investment should be almost persistently concentrated to the second region, as far as there is no change in the values of relevant parameters.Third, the resultant optimum solution is very sensitive to the relative sizes of such parameters ass _i, _i , _i (i=1, 2), and . Then, if there is some slight change in them by means of social overhead investment, for instance, which was analyzed earlier in this paper, we may observe a drastic change of the optimum solution. Such being the case, it may be possible for us to utilize some combination of those two kinds of public investment policy in order to attain theoptimum optimorum in the set of feasible growth paths.The author is a postdoctoral fellow with the University of Pennsylvania. The present paper is a product of his research on the basic theory of regional growth which has been supported by a grant from the Ford Foundation. This support is gratefully acknowledged. He is indebted to Professors W. Isard, B. H. Stevens, and J. Kissin for their valuable comments on the earlier draft of this paper. Of course, the author alone is responsible for any remaining errors.     

Migration analysis using data with time intervals of differing widths

Migration data collected for periods of differing lengths will yield inconsistent population forecasts, inconsistent multiregional life tables, and alternative interpretations of mobility levels and migration patterns. In this paper, examples are first given to illustrate the effects of migration interval choice on demographic variables. The moverstayer model and its generalizations are discussed in their role as models useful in achieving consistency. It is argued that in addition to theievel of mobility, the geographic pattern of migration flows is also affected by the choice of interval width.     

Effects of flame variation in ASTM D1692 flammability test

A study of various flame structures possible in the test for the flammability of cellular plastics showed that flammability characteristics could be appreciably altered by the selection of flame structure and position when testing highly flame-retardant rigid foams. Note: This paper was published in theJournal of Cellular Plastics, June 1967, and is printed here by permission.     

Practice-based learning in construction projects: a literature review

Construction project managers often face problems when trying to change work practices. Management research addresses these problems by offering stylized and abstract models; unfortunately, they may say little about the actual work practices that managers want to change. Practice theory offers an alternative way to address practice-related managerial problems, arguing that learning is a central enabler of performing practices. While some early research on practice-based learning in construction management exists, an understanding of how this theory has been applied is lacking. To address this limitation, a systematic literature review of 15 published construction management articles was conducted, the articles being divided into five practice-related analytical categories: participation, context, meaning production, power and becoming a practitioner to identify the areas of theory discussed. Participation and context were discussed more in the published articles than meaning production, power and becoming a practitioner, which might suggest that the latter categories offer more possibilities for future research. Further, the articles were analysed through a Lakatosian research programme lens, showing that a progressive research programme exists in practice-based studies in construction management. These findings provide avenues for future construction management studies seeking to apply practice-based learning theory to understand learning in construction projects better.     

Network facility-location models in Stackelberg-Nash-Cournot spatial competition

A hierarchical mathematical programming approach is combined with sensitivity analysis (of variational inequalities) to formulate a facility-location model for a firm competing on a discrete network. It is assumed that the locating firm will act as the leader firm in an industry characterized by Stackelberg leader-follower(s) oligopolistic competition. The othern competitors in this industry are assumed to act as Cournot firms that each operate under the Cournot assumption of zero conjectural variation with respect to theirn — 1 Cournot competitors. It is further assumed that then Cournot firms will react to the location/production/shipping activities of the Stackelberg firm. Therefore, when the Stackelberg firm makes its location, production, and shipping decisions it takes into account the reaction of then Cournot firms to its (the Stackelberg firm's) integrated location and distribution decisions. Specifically, a Cournot reaction function is developed and imbedded in the Stackelberg firm's profit-maximizing objective function to project the anticipated reaction of the Cournot firms to the Stackelberg firm's location decision.An earlier version of this paper was presented at the 37th North American Meetings, Boston, November 1990.     

TheGammarus: Asellus ratio as an index of organic pollution

Macroinvertebrate populations includingGammarus pulex andAsellus aquaticus were surveyed at riffle sites on four lowland rivers, i.e. the Rivers Adur and Ouse and the Chess Stream, Sussex, and the Eridge Stream, Kent. Sites were situated both upstream and downstream of sewage treatment works. Macroinvertebrates were collected using a Surber sampler and at some sites the water analysed for the main chemical constituents.Poor water quality is characteristically associated with low biotic scores and in this respect theGammarus : Asellus ratio applied to riffle data corresponded with the Chandler Biotic Score Index and the Extended Trent Biotic Index. TheGammarus : Asellus ratio showed the closest correlations with concentrations of BOD, ammonia-nitrogen (NH₃-N), nitrite-nitrogen (NO₂-N) and phosphate-phosphorus (PO₄-P) being sensitive to changes in water quality brought about by organic enrichment in the four rivers investigated.It is proposed that theGammarus : Asellus ratio may provide a simple biological tool which could be used by anglers and other non-professional river users to routinely monitor water quality.     

Undulating grounds,undisciplined bodies: the Soviet Rationalists and the Kinaesthesis of revolutionary crowds

In the turbulent political conditions of early modernity, the urban mass crowd emerged as a social phenomenon which presented demanding challenges to the arts: to innovate spatial formulations, graphic compositions and even aesthetic principles drawing on this new collectivity for legitimacy. Comparing the work of the Soviet Rationalist architects to the theatrical methods and productions by the Soviet revolutionary director V. E. Meyerhold, this paper probes the arts' responses to this crowd design problem. It discerns a spatial logic of ground-and-body: designers shaped theatrical sets and building surfaces to choreograph group ensembles as events, and to forge an alternative conception of space from the varying intensities of kinaesthetic bodily rhythms. Accordingly, the paper reflects on the nature of collective consciousness thereby evoked, and its distinct difference from another modernist state of consciousness: the paranoid individualism of panoptic inspection. It ventures to speculate that the Rationalists' architecture (and Meyerhold's theatre) effectively restores inter-subjectivity from its idealist discourse as an inquiry into other minds, to a problem of other bodies where subjectivity unfolds between emotional states at the body's expressive surface: the domain of generative spatial-design.     

Factor prices,factor proportions,and factor endowments in the pacific northwest: a regional test of the Heckscher-Ohlin theorem for then-factor case

A generalized version of the Heckscher-Ohlin model of trade has been developed by A. V. Deardorff for thel-factor,m-commodity, andn-country case. To test the validity of the Deardorff's model, first the factor content and commodity composition of trade between the Pacific Northwest (PNW) and the rest of the United States (ROUS) are estimated. These estimated values are then employed in a model to examine the degree of importance of relatively cheap energy and capital prices and relatively expensive wage rates in determining the level and composition of the PNW's trade with the rest of the United States. This study finds that the Pacific Northwest has a comparative advantage in the production of those goods which intensively use energy and capital and sparingly use labor in their production processes. This finding is, of course, in accord with the prediction of Deardorff's model.The author would like to thank Alan Deardorff and anonymous reviewers for their helpful comments on earlier versions of this paper.     

On a special class of boundary-value problems in the theory of shells and plates

This paper is concerned with problems in shell theory in which displacements are specified on a major surface of a three-dimensional shell-like body. It is unclear whether the theory of shells is in fact applicable to such problems; in virtually any treatment of shells, the equations of motion are derived by assuming that the tractions on both major surfaces are known. These known tractions manifest themselves as body forces in the resulting two-dimensional set of equations. We demonstrate in this paper that provided certain modifications are made, the latter set can indeed be used to solve problems in which displacements are specified on a major surface. These modifications are essential; they in fact reduce the number of differential equations and change the nature of the boundary conditions. We outline a clear procedure to treat such problems. The procedure is general in that it is valid for finite deformations of shells made of any material. We illustrate the efficacy of the final set of equations by presenting some examples from the linear theory of elastic plates.     

On the potential of genetic algorithms in urban drainage modeling

A genetic algorithm (GA) is a stochastic search algorithm that applies the biological concept of survival of the fittest in order to search for the optimal solution to a problem. In this paper we explore the potential and the benefit of using GAs for solving problems in urban drainage modeling. The main problem areas where such methods are assumed to have some benefit as compared to traditional procedures are identified from the literature as model calibration and model predictive control. The use of GAs for multi-criteria decision analysis is not reported in the context of urban drainage modeling but believed to be an interesting field of application. The methodology is discussed by means of benchmark problem sets for each of the applications.     

Around Madrid: the continuing influence of historical urban development plans on today’s periphery

This paper describes the peripheral development that has occurred in Madrid over the last 16 years (2000–2016), a period split by the economic crash that occurred in 2008. The paper argues that the relationship between economic development and infrastructure corridors witnessed in this peripheral development is intrinsically connected to the nineteenth and twentieth-century plans for urban growth. While these corridors have some similarities to the Strip model for an automobile city discussed by Robert Venturi and Denise Scott-Brown in their seminal book Learning from Las Vegas, the Madrid peripheries enjoy a long genealogy that complicates any easy link to the Strip, particularly around issues of economic speculation, typology and image-making or imagining, which will be introduced using the work of Michael Neuman and others. The research design adopted examines the treatment of the periphery in a number of historical plans, particularly their attitudes towards infrastructure and economic development, in order to establish connections between those historical plans and the city’s planned and (partially) realized peripheral development today.