Zied Hajej

Dr. Zied Hajej

Laboratory of Informatics Engineering, Production and Maintenance (LGIPM), Lorraine University, Nancy, France
orcid

Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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17 January 2011 in International Journal of Production Research
Verified
Journal Article
Closed access
ZHZied Hajej
Zied Hajej
DSDellagi Sofiene
Dellagi Sofiene
RNRezg Nidhal
Rezg Nidhal
This article deals with the combined production and maintenance plans for a manufacturing system satisfying a random demand. We first establish an optimal production plan which minimises the average total inventory and production cost. Second, using this optimal production plan, and taking into account the deterioration of the machine according to its production rate, we derive an optimal maintenance schedule which minimises the maintenance cost. A numerical example illustrates the proposed approach, this analytical approach, based on a stochastic optimisation model and using the operational age concept, reveals the significant influence of the production rate on the deterioration of the manufacturing system and consequently on the integrated production/maintenance policy.

5 November 2012 in Journal of Intelligent Manufacturing
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Journal Article
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ZHZied Hajej
Zied Hajej
DSDellagi Sofiene
Dellagi Sofiene
RNRezg Nidhal
Rezg Nidhal

18 November 2020 in The International Journal of Advanced Manufacturing Technology
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Journal Article
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ZHZied Hajej
Zied Hajej
NRNidhal Rezg
Nidhal Rezg
AGAli Gharbi
Ali Gharbi

5 May 2021 in Applied Sciences
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Journal Article
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ZHZied Hajej
Zied Hajej
ANAime C. Nyoungue
Aime C. Nyoungue
AAAminu Sahabi Abubakar
Aminu Sahabi Abubakar
MKMohamed Ali KAMMOUN
Mohamed Ali KAMMOUN
This article investigates integrated maintenance, production, and product quality control policy for a supply chain consisting of a single machine producing only one type of product, a main storage warehouse, and multi-purchases warehouses. The variation of the production rate and its use over time impact the manufacturing system’s degradation degree. Hence, the machine is subject to a random failure that directly affects the quality of the products. The goal of this study is to establish an optimal production and delivery planning with inventory management considering the production, holding, and delivery costs, and then an appropriate maintenance strategy, considering the influence of the production rate on the system degradation. Also, we provide a quality control policy to reduce the proportion of non-compliant products by using the statistical process control chart to forecast production. Forecasting the production aims to satisfy the varying demands during a finite horizon under service and quality levels. Numerical examples are presented to justify the effectiveness of the suggested strategy.

24 October 2019 in International Journal of Production Research
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Journal Article
Closed access
ZHZied Hajej
Zied Hajej
RNRezg Nidhal
Rezg Nidhal
CAChelbi Anis
Chelbi Anis
MBMaryem Bouzoubaa
Maryem Bouzoubaa
This paper presents an optimal integrated production and maintenance strategy for a wind farm. A cost model is developed in order to determine sequentially the optimal plan of energy production characterised by the number of working wind turbines and their production rates, and the optimal preventive maintenance policy to be adopted. We model the relationship between the variation of energy production rates and the failure rate of the wind turbines. A numerical example and a sensitivity analysis are presented and the obtained results are discussed.

7 April 2014 in International Journal of Production Research
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Journal Article
Closed access
ZHZied Hajej
Zied Hajej
NRNidhal Rezg
Nidhal Rezg
AGAli Gharbi
Ali Gharbi
In this paper, a forecasting production/maintenance optimization problem has been proposed with a random demand and single machine M1 on a finite horizon. The function rate of the machine M1 is depending on the production rate for each period of the forecasting horizon. In order to satisfy the customer, a subcontracting assures the rest of the production through machine M2 with transportation delay. An analytic formulation of the problem has been proposed using a sequential computation of the optimal production plan for which an optimal preventive maintenance policy has been calculated based on minimal repair. Firstly, we find, the optimal production plans of principal and subcontracting machines, which minimises the total production and inventory cost for the cases without and with returned products under service level and subcontracting transportation delay. Secondly, we determine a joint effective maintenance policy with the optimal production plan, which integrates the various constraints for the production rates, the transportation delay and the returned production deadline. Numerical results are presented to highlight the application of the developed approach and sensitivity analysis shows the robustness of the model.