João José de Assis Rangel

A simulation model to evaluate sugarcane supply systems

We present, in this paper, a simulation model to evaluate the sugarcane supply system to mills. The model addressed, on the whole, harvest operations (cutting and shipping), transportation and unloading at the mill (also considering the reception system of sugarcane within the mill). The model could adequately assess the relation of the freight, the lead time, the fleet of trucks and discount (opposite of agio), apart from the cost of cutting and shipping, related to the amount to be paid by the sugarcane load furnished to the mill.

Free and Open-Source Software for sustainable analysis in logistics systems design

The objective of this paper is to demonstrate how calculations of greenhouse gas emissions from transport in logistics systems can be analysed with Discrete Event Simulation models. For this, modelling was performed by considering the discrete aspects associated with transport systems with the continuous component of the carbon monoxide emissions from the fleet. The simulation models were constructed with the free and open-source software Ururau. The simulations searched to compare trade-offs of economic and environmental variables, in contrast to what is usually done in these types of systems, such as comparing economic variables with inventory variables. The results indicated that there is no direct relationship of proportionality between, for example, the delivery time and the total emissions produced by trucks.

Simulation model in a free and open-source software for carbon monoxide emissions analysis

This paper describes an analysis of emissions of carbon monoxide (CO) using a discrete event simulator of open source. A simulation model was built to evaluate gas emissions emitted by a fleet of trucks during transportation of raw materials in a typical supply system of sugarcane in producer mills of ethanol. The simulation model was implemented in the open source simulator and a traditional simulator. The model results presented high correlation, with no significant difference between them. It was also possible to contribute with the proposed simulator through a designed component able to account the CO emissions.

Ururau: a free and open-source discrete event simulation software

This paper has the purpose of describing the architecture and operation of Ururau, a software used to create discrete event simulation models based on the Java Simulation Library. Ururau is a free and open-source multiplatform software, which allows the user to develop models in the graphical interface or implement them directly in the source code. This characteristic allows the user to employ it as a tool for modeling and simulation of discrete event systems and also as a learning tool. Thus, an experienced modeler can add specific algorithms to simulation models or new features to the simulator. Also, with access to the source code, a beginner modeler can understand the internal structure of a discrete event simulation software. Initial results have demonstrated this new software’s ability in building small and simple models efficiently.

Discrete event simulation as didactic support to the teaching of telecommunications systems: applications in digital telephony

The development of telecommunications in Brazil demands increasingly skilled professionals. Professional training in this area is mainly acquired in the courses of technical and technological training. In the teaching of telecommunications, an alternative to the rapid technological progress and the cost of equipment for laboratory practice is the use of didactic simulators. Animation models were developed to represent concepts in digital telephony, specifically in time-division multiplexing, demultiplexing and switching time. Visualization tests were made with multimedia resource for the teacher in the classroom and with personal computers for each student in the computer lab. The models were adequate as an additional tool in teaching telecommunications and as a complement of the laboratory practice in the discipline of telephony. We noticed the potential of discrete simulation software to make animation models for technical and technological education in other subjects in the course of telecommunications.

Mathematical Modeling for Computational Simulation of the Temperature Distribution During the Synthesis of Polycrystalline Diamond

The properties and structural characteristics of polycrystalline diamonds synthesized at high pressure and high temperature are strongly influenced by the distribution of temperature inside the reaction chamber. This distribution cannot be directly measured during the graphite to diamond transformation. In this work a mathematical model associated with a computational analysis was developed to simulate the chamber, point to point, temperature distribution throughout the synthesis process. The simulation results obtained are in agreement with experimental data found in the literature. Moreover, it was possible to explain the restriction that exists regarding the use of graphites with different densities.

Use of IDEF-SIM to document simulation models

The technique of conceptual modeling IDEF-SIM uses the syntax of IDEFØ and IDEF3 adapted to the peculiarities of the simulation models. It allows the state variables and the logical elements of a discrete system to be abstracted and ordered with most representativeness. However, it is essential to establish additional measures that enhance the process of collecting and authenticating relevant data. This context has motivated this research, which suggests a model documentary that, when associated with the methodology IDEF-SIM, allows recording the details of a dynamic system in an objective and standardized way. We carried a study on a seaport, allowing verifying that the system was translated with greater speed and detail. In this sense, we concluded that the record out in detail increased efficiency in the generation of knowledge about the particularities of the system, regardless of the complexity of the problem and the computer language adopted.

Discrete event simulation for teaching in control systems

The objective of this work is to demonstrate the use of discrete event simulation to be employed as a didactic resource in automatic control systems classes. The application was made with the free and open-source software Ururau integrated to programmable logic controllers of manufacturing didactic stations. The result produced an environment for learning (simulation model and controllers). In this environment, the student can experience different practical situations with the simulation model and have direct contact with the real equipment.

Computer simulation of the mechanism for the synthesis of carbonado diamond

The synthesis mechanism associated with the formation of carbonado type polycrystalline diamond has been analyzed. This analysis was performed by computer simulation of the field of temperature developed at the moment of graphite transformation into polycrystalline diamond. It was found that during the synthesis of this carbonado diamond, a strong non-steady thermal condition occurs, leading to changes in the thermodynamic equilibrium. As a consequence, a region comprising non-transformed graphite and carbonado with different characteristics is established. An experimental comparison was carried out between the carbonado hardness profile and the field of temperatures. The results show that the higher the temperature attained at local points inside the high-pressure chamber, the higher the hardness of the diamond. The simulation and experimental results indicated that concurrent mechanisms are acting during the carbonado synthesis.

SIMULATION OPTIMIZATION FOR ANALYSIS OF SUSTAINABLE LOGISTICS SYSTEMS

This work analyzed different logistics structures under a sustainable perspective. It was developed a discrete event simulation model associated with optimization algorithm to evaluate the best combinations of the model. Besides, the comparison between the simulation optimization and a multicriteria method was performed. The simulation software Ururau, in which a model with optimization algorithm allowed testing different variables, was applied in order to find the best answer to the issue. Results showed that a connection of direct proportionality between variables of transport time, greenhouse gas emissions and lead time can happen. It was also checked that the solution returned by the simulation optimization was similar to the multicriteria method in most of the tests. The ones that differed were due to small mathematical precisions between the methods.