Christophe Sauvey

Heuristics and metaheuristics for mixed blocking constraints flowshop scheduling problems

Storage or buffer capacities between successive machines in flowshop problems may be unlimited, limited or null. The last two cases can lead to blocking situations. In flowshop scheduling literature, many studies have been performed about classical flowshop problems and also about some problems with only one blocking situation between all machines. This paper deals with makespan minimization in flowshop scheduling problems where mixed blocking constraints are considered. After a problem description and definitions of different blocking constraints, a mathematical model is presented and heuristics are developed to propose quick solutions to these kinds of problems. Then, metaheuristics are used to improve found solutions. A comparison between heuristics and metaheuristics is then performed.

A genetic algorithm with genes-association recognition for flowshop scheduling problems

In this paper, we consider a flowshop scheduling problem with a special blocking RCb (Release when Completing Blocking). This flexible production system is prevalent in some industrial environments. Genetic algorithms are first proposed for solving these flowshop problems and different initial populations have been tested to find which is best adapted. Then, a method is proposed for further improving genetic algorithm found solutions, which consists in marking out recurrent genes association occurrences in an already genetic algorithm optimized population. This idea directly follows Holland’s first statement about nature observations. Here, proposed idea is that populations well adapted to a problem have an adapted genetic code with common properties. We propose to mark out these properties in available genetic code to further improve genetic algorithm efficiency. Implementation of this method is presented and obtained results on flowshop scheduling problems are discussed.

Initial Populations Tests for Genetic Algorithm Flowshop Scheduling Problems Solving with a Special Blocking

Abstract In this paper, we consider a flowshop scheduling problem with a special blocking RCb (Release when Completing Blocking). This flexible production system is prevalent in some industrial environments. We propose genetic algorithms for solving these flowshop problems and different initial populations are tested to find the best adapted. Then, different parameters sets are tested in order to find the best for further genetic algorithms populations’ selection. Best parameters set and results are endly discussed.

Job-Shop Scheduling with Mixed Blocking Constraints between Operations

This paper addresses a hybrid job shop problem with identical machines, where several blocking constraints can be taken into account in a same problem. A mathematical linear integer model is proposed to be able to solve optimally the problem with commercial software. Since this problem is NP-hard, we developed an evaluation function in order to be able to solve bigger problems with classical meta-heuristics, thanks to a blocking matrix, containing the blocking constraints encountered after each operation of each job. The benchmark problems are proposed at the end of this paper, and the obtained results validate as much the proposed method as the evaluation function quality and suitability.

A 100kHz-2kW converter for switched reluctance rnotor used in high speed machining applications

This paper deals with the design and the realisation of a 100 kHz - 2 kW converter used to supply a three phased switched reluctance motor (SRM) for high speed machining (HSM) applications. The converter topology is described, and unlike some other applications, this converter is not a resonant one. This topology is justified with SRM magnetic losses and control aspect. In order to limit the iron losses at the rotor, stator electric phases are preferentially fed with bidirectional currents, this is the main reason why the full bridge converter is preferred. Converter power losses are then estimated, and dead-time delays are assessed to design driver control circuits. Several experimental waveforms, both in half-bridge and full-bridge modes, are finally presented and discussed

Parameters Identification of the Switched Reluctance Motor Without Position Sensor

Abstract This paper proposes a new method to identify the electrical and mechanical parameters of the mathematical model of a switched reluctance motor without the use of a position sensor. An analytical expression of the inductance law, using the least square solution, is done. The mechanical dynamic model of the SRM drive, which is linear in relation with the dynamical parameters of the drive is presented. The least square solution is used to estimate the dynamical parameters of the drive. Conditions for a good data processing before identification are presented through some aspects concerning data filtering.

Nonlinear Identification and Control of a Switched Reluctance Motor

Abstract This paper focuses on a method to identify the electrical and mechanical parameters of the model of a switched reluctance motor without any additional position sensor. An analytical expression of the inductance is obtained using the amplitude modulation method. Conditions for data processing before identification through some aspects concerning data filtering and estimation of the dynamical parameters are exposed. Then, the speed control of an SRM drive using the linearizing approach is developed. An internal loop with PWM amplifier is used to control the current of each phase. Simulations results, at low speed and high speed, are presented to validate the control method.