Multiple Markets and Spatial Agglomeration in a One Shopping Trip Model

This paper analyzes a spatial competitive monopolistic model of agglomeration in which households make only one shopping trip per period, and there are several firms in each industry. The model is a version of a model by Fujita (1988), but unlike his, in this model no equilibrium mixed district is possible, and a number of firm districts may appear. It is shown that allowing several firms in each industry may lead to a Mall equilibrium or an equilibrium with multiple shopping centers.agglomeration, bid-rent, land use, residential district, firm district

Barter Economies and Centralized Merchants

The main goal of this essay is to analyze the emergence of a barter economy, and the rise of centralized merchants and a barter redistribution system out of a primitive barter system. The environment is a spatial general equilibrium model where exchange is costly. Since exchange becomes more complicated as the scope of the economy increases, we prove that, after the economy reaches a critical size, the cost of trade expansion surpasses its benefits. This imposes limitations on the scope of the economy and the production level. To overcome these limitations, rational individuals can develop a more advanced barter system leading to the appearance of centralized merchants. This more sophisticated system is the redistribution system. We also show that under some circumstances, in the presence of transaction costs it may be optimal for individuals to keep using barter instead of adopting a monetary system. This result explains why some primitive economies, like the Incas in Peru and ancient Egypt, did not evolve to a monetary system, and kept barter as their main exchange system.

Inflation and Capital Structure

This essay is a contribution to the empirical literature on the effect of inflation tax on capital structure. A simple empirical model considering the main results of the current theoretical development is studied, using microdata from a number of American corporations.inflation tax, capital structure, firm value, debt-capital ratio

Multiple Markets and Spatial Agglomeration in a One Shopping Trip Model

This paper analyzes a spatial competitive monopolistic model of agglomeration in which households make only one shopping trip per period, and there are several firms in each industry. The model is a version of a model by Fujita (1988), but unlike his, in this model no equilibrium mixed district is possible, and a number of firm districts may appear. It is shown that allowing several firms in each industry may lead to a Mall equilibrium or an equilibrium with multiple shopping centers.

Inflation and Capital Structure

This essay is a contribution to the empirical literature on the effect of inflation tax on capital structure. A simple empirical model considering the main results of the current theoretical development is studied, using microdata from a number of American corporations.

Barter Economies and Centralized Merchants

The main goal of this essay is to analyze the emergence of a barter economy, and the rise of centralized merchants and a barter redistribution system out of a primitive barter system. The environment is a spatial general equilibrium model where exchange is costly. Since exchange becomes more complicated as the scope of the economy increases, we prove that, after the economy reaches a critical size, the cost of trade expansion surpasses its benefits. This imposes limitations on the scope of the economy and the production level. To overcome these limitations, rational individuals can develop a more advanced barter system leading to the appearance of centralized merchants. This more sophisticated system is the redistribution system. We also show that under some circumstances, in the presence of transaction costs it may be optimal for individuals to keep using barter instead of adopting a monetary system. This result explains why some primitive economies, like the Incas in Peru and ancient Egypt, did not evolve to a monetary system, and kept barter as their main exchange system.Barter, City, Exchange system, Market center, Merchant, Redistribution system, Transaction cost

The Appearance of Carriers and the Origins of Money

The main goal of this essay is to provide microfoundations in a spatial general equilibrium framework for the fact that individuals use money to make transactions, and hence microfoundations for the cash in advance constraint. We analyze the emergence of a monetary economy out of a redistribution barter system where goods are sent to a central market and then redistributed among individuals. We show that, as the population increases beyond a certain point, the barter exchange system becomes too expensive. To reduce the exchange system cost, and as a result of individuals’ rational behavior, a new specialized merchant, the carrier, appears and causes frictions among traders leading to the appearance of money. There are, however, certain conditions for this process to succeed. These conditions concern the economic characteristics of those goods chosen to act as money, and the level of economic development.Barter, Money, Carrier, Market center, City, Transaction cost

A Theoretical Model of Barter in Russia

This paper develops a general equilibrium model and proposes a theory to explain the main stylized facts about the growth of barter transactions in Russia during the 1990s. Because of the high opportunity cost of using fiat money, with a tight enough credit market it may be optimal for firms to barter if they have access to that transaction technology, yet the riskiest firm will keep using money. We also claim that, in the short run, Russian managers might avoid restructuring because it jeopardizes their access to alternative transaction technologies, and that this phenomenon might also take place in well-developed market economies.Barter; money; payment system; interest rate

The Appearance of Carriers and the Origins of Money

The purpose of this essay is to analyze the circumstances where a monetary economy dominates over a redistributive barter economy in which there is not an absence of double coincidence of wants problem. For this purpose, we develop a spatial general equilibrium model where individuals must trade with intermediaries to acquire the consumption goods that they need; exchange is costly, there is no trust, and individuals act in their own interest to maximize their utilities. The model is also used to address a number of issues in monetary economics like explaining the historical emergence of commodity-money, valued fiat money, the welfare-enhancing role of money, equilibria with several mediums of exchange, and split between the utility and the medium of exchange value of the good that serves as a medium of exchange. It also provides some interesting links between the monetary and urban economics literatures.barter; medium of exchange; city size; carrier; merchant; transaction cost

High-viscosity biphasic flow characterization in a pipeline: application to flow pattern classification and leak detection

Pipeline systems play an essential role in the oil industry. These systems connect ports, oil fields, refineries, and consumer markets[104]. Pipelines covering long distances require pumping stations, where products are propelled to the next pumping station, refinery, or deposit terminal, thus traveling through most of the country. The product considered in this research work is crude oil. It is usually transported with a combination of crude oil with viscosity reducers (DRA, drag reducer agent) and oil with gas in onshore/offshore pipelines. This mode of transport is efficient for large quantities and large product shipment distances. Problems may arrive when a leak occurs. In major incidents, large scale damage to humans and the environment is possible. Then, this research addresses the problem of how to detect the leak earlier to reduce the impact in the surrounding areas and economic losses, considering five research topics taking into account that the products inside the pipeline are water-glycerol and gas-glycerol mixtures (simulating oil-DRA and oil-gas in the laboratory test apparatus). The first research topic presents a mathematical model to describe the flow of a mixture of water and glycerol in pressurized horizontal pipelines, which emulates the mixture of heavy oil and a viscosity reducer. The model is based on the mass and momentum conservation principles and empirical correlations for the mixture’s density and viscosity. The set of partial differential equations is solved using finite differences. These equations were implemented in a computer platform to be able to simulate a system. This simulation platform is a tool to simulate leak cases for different fractions of water and glycerol to evaluate algorithms for leak detection and localization before their implementation in a laboratory setting.DoctoradoDoctor en Ingeniería Mecánic