Shipment Patterns Research Articles

The Portuguese Slave Trade from Angola

Ever since Philip Curtin's census of the Atlantic slave trade was published in I 969, historians have been preoccupied by attempts to quantify the slaves exported from Africa by various national carriers between I 500 and I 870 and the levels and patterns of slave mortality in the middle passage. Given the title of Miller's book, one might be forgiven for assuming that his lengthy study of the Angolan slave trade follows this established pattern, particularly since Miller himself has made important contributions in the past to quantifying this branch of the trade. A survey of the contents of the book soon undermines such an assumption, however, for although Miller provides a brief summary of slave exports from Angola (pp. 228-34) and the story of the slaves and the appalling levels of mortality they suffered during their terrible journey from the Angolan interior to the shores of Brazil figure prominently in his book, the reader will search in vain through its 770 pages for an integrated analysis of long-term trends in slave exports and other time series in the Portuguese slave trade from Angola. The relegation of the quantitative aspects of the trade to a supporting role in Miller's study reflects to some extent his scepticism about the available trade statistics, most of which derive from official tax records and are, he believes, too unreliable to permit 'the formal statistical and economic analysis that has informed much recent work on the Atlantic slave trade' (p. xvi). But it also arises from the fact that Miller's primary concern is not with the levels of trade per se, but with the principal actors in the business African rulers and lineage heads, Luso-African merchants and colonial officials based at Luanda, Brazilian shipowners, and Lisbon tax contractors, merchants and trading companies and how their attitude toward and involvement in it shaped its internal structure and organization. This is an ambitious and formidable undertaking, for not only did the roles and levels of participation in the trade of those associated with it vary over time, but the commercial, political and, ultimately, cultural and ideological worlds in which they operated differed greatly and changed significantly in the period that he covers. Moreover, the evidence available to Miller for assessing the perceptions and motives of the key players in the trade and how these shaped their behaviour and the trade's structure largely derives from the records of the colonial authorities, which, given their 'eloquent silences' (p. xxiii), are far from ideal for his purposes. By his own admission, important parts of his argument depend, therefore, upon inferences and interpretations drawn from slender and contentious evidence and assumptions, and can, and no doubt will, be the subject of criticism and revision. Nevertheless, in terms of the insights that it provides into the organization of the Portuguese slave trade, particularly at Luanda, and the general scope and range of issues that it confronts, this is unquestionably a notable addition to the literature on the Atlantic slave trade. Those familiar with Miller's previous work, most of which has centred on precolonial Angola and the pattern of slave shipments from the region, will be

The Changes in Shipment Patterns of Petroleum Since Two Oil Crises in Japan : From the Viewpoint of Supply, Demand and Transportation

The Changes in Shipment Patterns of Petroleum Since Two Oil Crises in Japan : From the Viewpoint of Supply, Demand and Transportation

Sensitivity Analysis for the General Spatial Economic Equilibrium Problem

We consider the general spatial economic equilibrium problem where the supplies and demands at each market for each commodity may depend on the price on this as well as other prices of other commodities at other markets and the transportation cost on each link for each commodity may depend on the flow on this as well as other flows of other commodities on other links in the network. For this model we perform stability and sensitivity analysis. Assuming that the supply, demand, and transportation cost functions are monotone, we first show that the multicommodity equilibrium price pattern depends continuously upon the market supply and demand functions and the multicommodity equilibrium shipment pattern depends continuously upon the transportation cost functions. We then focus on the delicate question of predicting the direction of the change in the price and shipment pattern and the incurred supplies, demands, and transportation costs resulting from changes in the supply, demand, and transportation cost functions and we demonstrate that certain phenomena may prevail. Our analysis depends crucially on the fact that the governing equilibrium conditions can be formulated as a variational inequality.

Stability, sensitivity analysis, and computation of competitive network equilibria : Anna Nagurney, 1983 (Dissertation in the division of Applied Mathematics, Brown University, Providence, RI 02912)

Competitive network equilibrium problems originate in situations where each user of a network acting independently seeks to minimize his personal disutility until, finally, an equilibrium is established characterized by the property that no user has any incentive to change his strategy, given that all other users retain their present strategies. Such competitive equilibrium problems, that arise in economics, operations research, and control theory can be formulated as a variational inequality. Although a plethora of algorithms is available for determining the equilibrium, relatively little effort has been extended towards the computational testing of these algorithms. In addition, the important for the applications questions of stability and sensitivity of the equilibrium have not been addressed yet in any general context. In this thesis we study the stability and sensitivity of the equilibrium for two applications, namely, the traffic equilibrium problem and the spatial economic equilibrium problem. We consider the general asymmetric traffic equilibrium problem with fixed demands. We show that, under certain assumptions, the equilibrium traffic pattern depends continuously upon the assigned travel demands and travel cost functions. We then focus on the delicate question of predicting the direction of the change in the traffic pattern and the incurred travel costs resulting from changes in the travel cost functions and travel demands and attempt to elucidate certain counter-intuitive phenomena such as Braess paradox. Next we consider the general spatial economic equilibrium problem. Under certain conditions we show that the multicommodity equilibrium price pattern depends continuously upon the market supply and demand functions and the multicommodity equilibrium shipment pattern depends continuously upon the transportation cost functions. We then address the important question of predicting the direction of the change in the price and shipment pattern and the incurred supplies, demands, and transportation costs resulting from changes in the supply, demand, and transportation cost functions. Finally, we proceed to test the relative efficiency of the main computational techniques for computing the solution of the variational inequality, the relaxation and projection methods. Our results indicate that the form of certain functions affects the performance of the two basic techniques.

Costs and distortion of U.S. regulation policy in intercoastal lumber shipping

This article quantitatively analyzes the various impacts of current U.S. coastal restrictions on the Northwest lumber industry. The history of U.S. maritime regulation is briefly reviewed and a simulation model is developed to measure its affect on lumber shipments and transport costs. The results of the model indicate that aggregate cost redutions obtained through deregulation are likely to be small. The pattern of intercoastal shipments could change a great deal, however, with U.S. producers picking up a large share of the Northeast market.

Lumber Transport and the Jones Act: A Multicommodity Spatial Equilibrium Analysis

This article examines the impact of current coastal trade restrictions on American intercoastal lumber shipping. The nature of U.S. maritime regulation is briefly reviewed and a model is developed to quantify its effect on lumber shipments, shipping costs, and economic welfare. It is found that the aggregate cost reductions and welfare gains resulting from deregulation will most likely be of little significance. Regional welfare redistributions will be fairly substantial however, as lower transport rates significantly alter the pattern of intercoastal shipments and allow Northwest U.S. producers to capture a large share of the Northeast market from their Canadian competitors.

Multiple goal production and logistics planning in a chemical and pharmaceutical company

This paper is concerned with the development of a model for aiding management decision making in a multiple product chemical and pharmaceutical processing environment. The situation considered is one with several manufacturing locations and transshipment points over several time periods. A multiple goal model is developed to aid decision makers in determining both production and shipment patterns while considering various goals, such as: (i) minimization of the deviation from the desired level of total costs; (ii) minimizing the deviations from the goal levels for final inventories; (iii) minimizing the deviations, from their desired goal levels, of the amounts of certain items that are produced at various plants and/or shipped over certain routes.

Least-Cost Milk Assembly and Manufacturing Plant Locations for the Northeastern Dairy Industry

There is some concern that geographic patterns of dairy cooperative membership, and customary relationships among milk assemblers and processors, may inhibit milk marketing efficiency in the Northeast. Raw milk assembly patterns and hard product manufacturing plant locations are here developed which minimize total regional costs of these functions. Solutions are highly sensitive to season, day-of-the-week, and capacity assumptions. Evidence strongly suggests that regional coordination of milk assembly and manufacturing would result in cost savings and in some re-alignment of present milk shipment patterns.

Determining optimal growth paths in logistics operations

AbstractThis paper considers a logistics system modelled as a transportation problem with a linear cost structure and lower bounds on supply from each origin and to each destination. We provide an algorithm for obtaining the growth path of such a system, i. e., determining the optimum shipment patterns and supply levels from origins and to destinations, when the total volume handled in the system is increased. Extensions of the procedure for the case when the costs of supplying are convex and piecewise linear and for solving transportation problems that are not in “standard form” are discussed. A procedure is provided for determining optimal plant capacities when the market requirements have prespecified growth rates. A goal programming growth model where the minimum requirements are treated as goals rather than as absolute requirements is also formulated.

Interregional competition in the United States turkey industry

The purpose of this study is to predict the future locational changes of the turkey industry, both in the short and long run, with particular attention given to the competitive position of California. Three spatial equilibrium models, including 60 producing and 58 consuming regions, are developed. The components of the various models include regional production and processing costs, regional demand and supply functions, and transportation costs. The short-run ex post model suggested that, given the present location of production and consumption in the United States, the transportation of turkey follows reasonably efficient shipment patterns. The short-run ex ante model predicted prices, quantities, and shipments by region recursively for the three-year period 1962-1963-1964, based on data available in 1961. Predictions for the first year were reasonably accurate, but errors tended to accumulate beyond this. The long-run ex ante model predicted a long-run relocation of the industry, with concentrations of production in the Midwest and South, with the West (including California) dropping out of turkey production. Various policies designed to improve California’s long-run competitive position were examined, using the interregional models. Neither a uniform United States minimum wage of up to $1.25 per hour nor a 50 per cent reduction in transportation rates on dressed turkey exports from California would prevent the state from being a net importer of turkey. Transportation rates on feed inshipments would need to be reduced nearly 40 per cent for California to remain even self-sufficient in turkey production. The interregional models also were used to examine certain aspects of the 1962 turkey marketing order. Freezing production location by historical allotment could increase the aggregate production and processing cost of meeting long-run demand by up to 14 per cent. Adapted to the specific case, and supplemented with judgment and political considerations, the models could be useful in assessing the effects of various types and levels of production control and even in the administration of such programs.

Regional location of cattle feeding — A spatial equilibrium analysis

This study focuses on factors affecting the regional location of cattle feeding. Briefly stated, these factors include the regional demand for beef, transfer costs for carcass beef and for the intermediate products of feeds and feeder cattle, feed conversion efficiency by region, and regional supplies of the intermediate products of concentrate feed, hay, and feeder cattle. The study is a partial equilibrium approach to the location of feedlots, taking as given the location of production of other livestock products. A competitive equilibrium model was developed for analyzing the location of cattle feeding for a 20-region breakdown of the United States for the 1957-58 feeding year. A linear programming technique was utilized to quantify the model. The solution generated provides the spatial distribution of cattle feeding by region, the pattern of interregional shipments of intermediate products and of carcass beef, a set of equilibrium prices for beef, and imputed prices for intermediate products by region. Four models were quantified to test alternative model specifications as to feedlot nonfeed costs, regional feed conversion efficiency, and regional demand for beef. Results indicate no simple rules for location of cattle feeding, but rather stress the importance of considering the interrelationships among the major variables such as the regional demand for beef, regional intermediate product supply, regional feed conversion efficiency, and transfer costs for the intermediate products and for carcass beef.

Methodology and Implications of Spatial Equilibrium Solutions in the Pork Sector of the Livestock-Meat Economy

A S THE linear programming literature of the 1940's reflected the growth of the transportation model, so the decade of the 1950's witnessed the development of spatial equilibrium models from theoretical exposition to empirical application. Both models seek to determine optimum shipment patterns for trade of a product among three or more market places within a rather perfectly competitive market area where the amount of the commodity produced is equal to the amount consumed. When the solution is derived with a transportation model, an optimum shipment pattern is reached when all destination requirements have been satisfied and total transportation costs have been minimized. The solution yields the total transportation bill and discloses the direction and volume of trade between each possible pair of regions. When the more penertating spatial equilibrium approach is employed, the equilibrium relationship discloses not only volume, direction and cost of shipment, but also per capita consumption and price per unit in each region. An optimum pattern is attained when all destination requirements have been fulfilled, total transportation cost has been minimized, and product value-added, therefore, has been maximized. This paper constitutes a progress report on current investigations at the Ohio Agricultural Experiment Station into the interregional nature of the hog-pork sector of the livestock-meat economy. Five, 27-region U. S. models for 1960 and five, 29-region models for 1975 attempted to incorporate variations which would yield insights that might otherwise remain unquantified: (1) Liveweight transportation rates were incorporated independently of volume but not of direction of shipment. (2) Implications of slaughter location were examined on the basis of both procurement and distribution patterns provided by optimum shipment solutions for live animals to slaughter together with shipment patterns of meat from slaughter to consumption. (3) Regional boundaries were

On the Numerical Solution of the Transportation Problem

The linear transportation problem consists in finding a pattern of shipments between m origins with given surpluses and n destinations with given deficits such that the total cost of transportation is minimized. The method of solution proposed here is iterative and will lead to the optimum in a finite number of steps. It involves finding a good first approximation by simple inspection and improving it by successive adjustments. The earlier stages of the proposed method are less laborious than the simplex method, but the latter has the advantage when the adjustments become more complicated. The proposed method may therefore be used as a starting approach to be followed by the simplex method if the optimum is not reached with simple adjustments only. Operations Research, ISSN 0030-364X, was published as Journal of the Operations Research Society of America from 1952 to 1955 under ISSN 0096-3984.