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Reducing Flow Time in an Automotive Asynchronous Assembly Line – An application from an automotive factory

El Ahmadi Salah Eddine Ayoub, El Abbadi Laila

Management and Production Engineering Review

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2022

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Vol. 13, No. 1

99--106

EN

The automotive industry is a highly competitive sector. Manufacturers must effectively control highly complex production processes in order to fulfil all customer orders for customized cars on time, on budget and to the required quality. In this paper, the authors focus on improving the flow time of asynchronous automotive assembly lines by reducing the buffer time. A simulation-search heuristic procedure was developed and confirmed in a 5 workstations asynchronous assembly line installed in an automotive company. The proposed procedure identifies optimal performing buffer profiles for each storage level which guarantees lowest flow time while keeping the same throughput level. Experiments results show that our new algorithm significantly outperforms existing results, especially for large scale problems.

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Berth Allocation Problem: Formulation and a Tunisian Case Study

Kallel Lobna, Benaissa Ezzedine, Kamoun Hichem, Benaissa Mounir

Archives of Transport

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2019

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Vol. 51, iss. 3

85--100

EN

This paper examines one of the most important operational problems in seaport terminals, namely the Berth Allocation Problem (BAP) which finds an optimal assignment of ships to the berths that minimize the total waiting time of all ships and reduce congestion in ports. Our problem is to affect and schedule n ships on m berths to minimize the processing time and the waiting time for all the ships in the port. Therefore, ships stay time in the port known by the flow time, while respecting the physical constraints existing at the port (such as the depth of the water berth and the draft of the ship’s water), knowing that each ship can only accommodate one ship at a time. It is as if it was a case of n tasks and m machines in parallel, and we wanted to schedule the passage of different tasks on different machines, knowing that each task can only pass on one machine and that the interruption of the task is not allowed. For example, if a job started on a machine, it will remain on this machine up to its completion. In our case, tasks are ships and machines are berths that are opting to minimize the total flow time and, therefore, to decrease the residence time of all the ships in the port. In a first step, a Mixed Integer Linear Program model is designed to address the BAP with the aim of minimizing the flow time of the ships in the port, our sample can be used for both static and dynamic berth allocation cases. In a second step, this model is illustrated with a real case study in the Tunisian port of Rades and solved by a commercial solver CPLEX. Calculation results are presented and compared with those obtained by port authorities in Radès.

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Wiskozymetryczne materiały odniesienia i wzorcowanie kubków wypływowych

Ruśkowska P.

Metrologia : biuletyn informacyjny Głównego Urzędu Miar

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2010

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nr 1

10--18

PL

Wybór metody pomiaru lepkości oraz odpowiedniego typu przyrządu pomiarowego zależy od właściwości fizykochemicznych badanej cieczy oraz od warunków pomiarowych. Lepkość cieczy o specyficznym składzie chemicznym, takich jak farby i lakiery, jest często oznaczana za pomocą wiskozymetrów kapilarnych zwanych kubkami wypływowymi. W niniejszym artykule zdefiniowano pojęcie lepkości dynamicznej i lepkości kinematycznej cieczy oraz omówiono kapilarne wiskozymetry wypływowe. Przedstawiono metodę wzorcowania wiskozymetrycznych materiałów odniesienia wytwarzanych i stosowanych w Zakładzie Fizykochemii Głównego Urzędu Miar oraz omówiono metodę wzorcowania kubków wypływowych z dnem stożkowym.

EN

In the field of viscometry, the choice of an appropriate measurement method and a type of the measuring instrument depends largely on physicochemical properties of the liquid and on measurement conditions. Viscosity of liquids of specific chemical composition, such as paints and varnish materials, is often measured with the use of capillary viscometers called flow cups. In this article, I define dynamic viscosity and kinematic viscosity and describe a few types of the outflow capillary viscometers. I give the method of calibration of viscosity reference materials produced and used in the Department of Physical Chemistry of the Central Office of Measures (GUM) and discuss the method of calibration of flow cups with cone-shaped bottoms