Bruno de Athayde Prata

A Branch-and-Bound Algorithm for Optimal Pump Scheduling in Water Distribution Networks

Nowadays water distribution operation systems are accomplished with the aid of qualified professionals who use their experience in order to achieve a satisfactory performance of the several hydromechanical devices, which are part of the system, such as boosters and valves. In general, these operational rules are empirical and the main goal is to assure the availability of water for the population, with no special concerns about saving energy used in pumping systems. Besides, these empirical rules often disregard hours of lower energy rates. There are several research works concerning the developments of operational rules optimization applied to specific water distribution systems. However, in this work, a general optimization routine integrated with EPANET is presented, which allows the determination of strategic optimal rules of operation for any type of water distribution system. Moreover, a Branch-and-Bound algorithm is also used, where finding the global optimal solution is guaranteed, in admissible computational times. The water distribution system used in this work corresponds to a hypothetical network proposed in the specialized literature.

Distribution of Materials in Road Earthmoving and Paving: Mathematical Programming Approach

This paper summarizes a mathematical model that relates the geometric and geotechnical features of a road construction site with the allocation of materials, searching for a minimum construction cost. This paper proposes a linear programming model to optimize excavation and paving services. With this model, it is possible to evaluate site alternatives with different soil strata and different degrees of compaction. The borrow pit materials are allocated in the most economical way, and it is possible to incorporate more inputs like materials mix. Software was used to solve the model, and a spreadsheet application was used as an interface for data input. The proposed model demonstrated possible cost savings in earthwork planning. It is expected that earthwork and paving optimization with linear programming will reduce road construction costs considerably.

An Integer Linear Programming Model for the Multiperiod Production Planning of Precast Concrete Beams

AbstractUnlike conventional beams, which are cast in the construction site, precast beams are cast in a production line in a beam factory. Their use may considerably reduce the completion time of construction projects, making them attractive to public housing. A key factor for the success of their use is the ability of efficiently producing them, which depends on the quality of the production planning. The objective of this paper is to propose an integer linear programming model for the precast concrete beams production problem. It is first shown that this problem is isomorphic to the well-known multiperiod cutting stock problem. The objective function is the minimization of the production loss of a production order, subject to the available capacity of forms used to cast the beams. A case study is presented with data of a real scale instance, so as to demonstrate the applicability of the model in industrial settings. The proposed model was implemented and ran on the CPLEX solver, which reached an optimal...

Avaliação da eficiência dos portos utilizando análise envoltória de dados: estudo de caso dos portos da região nordeste do Brasil

The port system is a key element for the macroeconomic development of its area of influence. The performance evaluation of the port sector becomes fundamental to the monitoring and improvement of the activities of this sector aiming at accomplishing efficiency. The Data Envelopment Analysis – DEA is a method based on mathematic programming which analyzes, based on the inputs and outputs utilized in a certain process, the efficiency of a set of Decision Making Units – DMU. This paper aims to elaborate and analyze models for the efficiency measuring of the ports in Brazil’s northwest in 2006, adopting the DEA method. The variables selection was done with the aid of the Compensatory method of Normalization (Single Parameter), which determines the variables to be utilized through index S that depends on the average efficiency (causal relation) and the quantity of DMU in the frontier (discrimination power). The facilities of containers and solid bulks of the main ports in northwest were analyzed. The obtaining of the port efficiency executed by the type of load helps in the medium and long-term planning, so that it organizes the ports to increase the timetable turnover and the loads turnover, contributing to the efficiency of the terminals.

A mixed integer programming approach for freight railcar distribution

The attendance of the demand for freight transport is related to the process of allocation of the wagons that in turn is associated with the way in which the decision is taken. The distribution of wagons to the shipment terminals depends on the planning as well as on movement of the empty wagons. In addition, the trips of the empty wagons have the major financial impact on the railroad system. In such a way, an efficient mechanism of wagon distribution is vital to the railroads, because it provides important operational profits and of costs. Therefore, the purpose of this study is to analyze the problem related to the distribution of the load wagons and to develop a mathematical model that can propose an optimal scheduling of the wagons.

Rolling Surface Evaluation Model Considering Topographic, Geotechnical, and Climatic Aspects in Low-Volume Roads: Case Study in Aquiraz, Ceará, Brazil

This paper presents an innovative model for assessing surface conditions in low-volume roads. The proposed approach focuses on intemperate weather influences (e.g., rain, wind), traffic, soil type, and relief in the reduction of the level of service of the unpaved road. It is concerned with the evolution of distress present in unpaved roads. The intention is to improve the performance evaluation method for surface conditions proposed by Correia et al., the ALYNO method. A case study is presented for the municipality of Aquiraz, Ceará, Brazil. A mathematical model is developed to forecast a performance evaluation model by using a topographical survey of unpaved roads; the result is the modified method called ALYNOMO. The main performance evaluation methods of surface conditions for unpaved roads are also studied. Several considerations about the geometric evolution of distress according to the usefulness of the studied branch are drawn from the case study. This research contributes toward improving the unpaved performance evaluation process and the ALYNO method, proposing a model to forecast the performance for regular and appropriate unpaved roads. The need for rational maintenance of this type of road is emphasized.

Restrições de controle sobre cores decompostas: uma proposta no controle supervisório de sistemas a eventos discretos utilizando redes de Petri coloridas

This paper presents the mathematical proof of the method for the synthesis of supervisors called Constraint of Control on Decomposed Colors, which is based on concepts of Supervisory Control Theory, using as main tool the coloured Petri nets to model systems discrete event, in order to find supervisors that meet those systems subject to constraints. By extension, it is proposed a method to reduce the number of controllers called Fusion of Controllers.