José Vicente Caixeta Filho

Gerenciamento da coleta de resíduos sólidos urbanos: estruturação e aplicação de modelo não-linear de programação por metas

This work presents a methodology that has been developed and applied to help the decision-making process, at both tactical and operational levels, in solid urban waste management. This methodology, based on an optimization mathematical model of Non-Linear Goal Programming, has been applied to Piracicaba, a city in the State of Sao Paulo. Some problems in tactical and operational management of solid urban waste collection have been found there, such as lack of standard collection of all the waste generated in some areas, non-optimization of fleet of vehicles available, productivity above that established as optimal in most areas, densities below or above average, among others. Furthermore, the need of restructuring collection areas has been noticed so that management can be more effective. Upon applying the model, it was concluded that such tool is useful in tactical and operational decision-making, as well as in helping redefining strategies to be followed by decision-makers.

Suinocultura no Estado de Goiás: aplicação de um modelo de localização

The main purpose of this research work was to analyse the most efficient spatial distribution of pig production units in the state of Goias. The model developed required a mixed integer programming structure. The factors considered in the model were: the grain transportation cost (corn and soybeans) from the source to the production unit, the cost of transporting the animals from the production unit to slaughterhouses and the carcass transportation cost from the slaughterhouse to retailers. The consumption market was spatialy defined as comprising the state of Goias, the Distrito Federal and the counties of Sao Paulo, Rio de Janeiro and Belo Horizonte. Moreover, it was determined the supplies of corn and soybeans for each microregion in the state of Goias and the national per capita pork consumption. Three scenarios, showing different per capita consumption levels, were considered. One of these is the current per capita consumption level and the two other were determined according to sector perspectives.

Fitting a taper function to minimize the sum of absolute deviations

Multiple product inventories of forests require accurate estimates of the diameter, length and volume of each product. Taper functions have been used to precisely describe tree form, once they provide estimates for the diameter at any height or the height at any diameter. This study applied a goal programming technique to estimate the parameters of two taper functions to describe individual tree forms. The goal programming formulation generates parameters that minimize total absolute deviations (MOTAD). These parameters generated by the MOTAD method were compared to those of ordinary least squares (OLS) method. The analysis used a set of 178 trees cut from cloned eucalyptus plantations in the Southern part of the state of Bahia, Brazil. The values of the estimated parameters for the two taper functions resulted very similar when the two methods were compared. There was no significant difference between the two fitting methods according to the statistics used to evaluate the quality of the generated estimates. OLS and MOTAD resulted equally precise in the estimation of diameters and volumes outside and inside bark.

Modelo de programação linear para seleção de pulverizadores agrícolas de barras

The selection process of agricultural machines is one of the most important stages of the productive process. The purpose of the present work was to develop and to test a linear programming model to aid in the decision of agricultural boom sprayer selection based on the cheapest hour-cost. The technical information about 20 sprayer models available in the market was used, where four were self-propelled, eight were trailed and eight were lift mounted sprayer. The sensibility analysis of the operational cost components showed that the repair and depreciation rates are the factors that most contribute to hour-cost variation of the sprayer-tractor group. The developed mathematical model facilitated the accomplishment of the sensibility analysis, which was processed in a very short time.

Caracterização do mercado de fretes rodoviários para produtos agrícolas

The Brazilian highway freight market is subject to no sort of government control, meaning that the prices are formed through free negotiation between supply and demand of the transport service. Carriers have to be updated on every variable incorporated in costs to be fit for negotiating with demanders. These demanders, except under certain very specific circumstances, have performed higher negotiation power and exerted quite strong pressure to obtain freight discounts. Taking into consideration the accomplishment of the quality of freight information, for both supply and demand sides of the transportation service, data for selected agricultural commodities were collected, as well as the identification of the main characteristics of the road haulage. The difference in the freight values for each commodity was noted, as was the distinct freight market structure for grains (sugar, corn, soybeans and soybean meal), which has been more spread out and perhaps less professional if compared with the transportation market for liquids, such as orange juice and soybean oil.

Impactos econômicos e ambientais decorrentes do estado de conservação das rodovias brasileiras: um estudo de caso

This article evaluates economic and environmental impacts of Brazilian highway conditions. The economic benefits evaluated were: diesel consumption, travel time and vehicle maintenance; the environmental benefits evaluated were the reduction on negative externalities related to decrease on carbon dioxide (CO2) emissions. Primary computer collected data related to the trucks performances on highways with different infrastructure conditions. The data were derived from 20 trips over 2 routes, each route representative of one of two highway conditions: better or worse (Campo Grande to Santos, and RondonA³polis to Campo Grande). The results had confirmed economics and environmental benefits resulting from travel over the better routes.

Valoração de atributos de qualidade em pêssegos comercializados no estado de São Paulo

Econometric models were developed to estimate the implicit prices for selected quality attributes of fresh peaches commercialized in the state of Sao Paulo. Such estimation is conducted in two stages of the distribution chain, namely, wholesale and retail sales. Data on the price and quality attributes (such as color, size, varieties and types of damages) of fresh peaches were obtained from cross-sectional data in different time periods. The estimation of Hedonic Prices is proposed as a method to evaluate post-harvest price variations from wholesale to retail sales. The results obtained allowed us to identify the gains accrued in each stage, deriving from the improvement in the product quality attributes.

Modelagem e gestão das perdas no suprimento de tomates para processamento industrial

The supply of tomatoes for the manufacturing process is a quite complex activity. Everyday large amounts of vegetables and fruits to be processed need to be stored. Their perishability has to be considered and the harvest is still manual in the majority of producing areas. Evidences show the existence of high levels of losses in the supply logistic process. A mathematical model was developed with the objective of allowing better knowledge of the whole process and investigating possibilities of optimization. The simulation using the model can generate scenarios that when compared with real performances show the importance of an accurate management with evident potential of expressive financial gains in the supply chain process with the reduction of time, losses and costs. The losses of products, which are regularly more than 2%, could be reduced to less than 1% and the option of not operating at full production capacity could also lower the costs generating higher revenues. To a plant with a processing volume of 336 thousand tons per season, the improvements of the supply process could result in gains estimated in R

Potencial da logística ferroviária para exportação de açúcar em São Paulo: recomendações de localização para armazéns intermodais

6 millions.

Otimização dos aterros sanitários

This study analyzes the best warehousing location for sugar exportation in the state of Sao Paulo using the railway transportation. A mixed integer programming model was developed and its results indicate some trends for localization and capacity of these warehouses. Four scenarios were elaborated and they showed high competitiveness of the intermodal transport compared to the alternative of road transportation from the mill to the port. It was also confirmed that there is a possibility to increase the market share of the railway transportation for Sao Paulo’s sugar exports.