Dynamic programming (DP) provides the optimal global solution to the energy management problem for hybrid electric vehicles (HEVs), but needs complete a-priori knowledge of the driving cycle and has high computational requirements. This article presents a possible methodology to extract rules from the dynamic programming solution to design an implementable rule-based strategy. The case study considered is a series/parallel HEV, in which a clutch allows to switch from one configuration to another. The strategy works according to a two layer policy: the supervisory controller, which decides the powertrain configuration (either series or parallel), and the energy management, which decides the power split. The process of deriving the rules from the optimal solution is described. Then, the performance of the resulting rule-based strategy is studied and compared with the solution given by the dynamic programming, which functions as a benchmark.

Dynamic programming is known to provide the optimal solution to the energy management problem. However, it is not implementable online because it requires complete a-priori knowledge of the driving cycle and high computational requirements. This article presents a methodology to extract an implementable rule-based strategy from the dynamic programming results and thus build a near-optimal controller. The case study discussed in this paper focused on mode switching in a series/parallel hybrid vehicle, in which a clutch may be used to change the powertrain topology. Because of the complexity of the system, the controller is divided in two layers: the supervisory controller, which decides the powertrain configuration, and the energy management, which decides the power split. The process of deriving the rules from the optimal solution is described in detail. Then, the performance of the resulting rule-based strategy is studied and compared with the solution given by dynamic programming, which functions as a benchmark. Then another comparison is performed with respect to the equivalent consumption minimisation strategy (ECMS) which, if optimally tuned, can achieve optimal performance as close to DP as possible with the advantage of being implementable.

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In our 2 previous papers published in this Journal, we had 5 cases of uterine malignancies developing after long term use of IUCD's. In the present paper 2 cases of such association are to be added. One case ATH with right adnexectomy was performed for persisting vaginal bleeding after 22 years of Lippes Loop application and recurrence 8 years after the first operation. Pathological diagnosis is endometrial stromal sarcoma. The other case is a leiomyosarcoma developing after 25 years of Lippes Loop application. Although no cause and effect relationship between IUCD use and uterine malignancy in human beings has been proved, the increase in such cases suggests to us that long term application should be avoided, particularly in view of the positive animal experiments. The successive detection of such cases in a relatively short period of time prompts us to make further studies to gain a deeper insight into such associations.