Study on the test load for the structural test of the flight-load condition of the external fuel tank for fixed-wing aircraft

In this study, for the purpose of conducting the structural tests for the verification of structural soundness of the flight-load conditions of the external fuel tank for the fixed-wing aircraft, the flight load acting on the external fuel tank was converted to test load and the suitability of the converted loads was verified. The loads imposed on the external fuel tank were expressed as the combination of the inertial load (based on the acceleration in the translational direction) and the tangential direction inertial load (based on the angular acceleration of the moment). To calculate the test load, the transfer function table was generated by calculating the shear load and moment based on the unit load. For this purpose, a transfer function table was established by dividing the external fuel tank into a few sections and calculating the shear load and moment generated by the unit shear load and unit moment in each section. In addition, the test load for each section was calculated by computing the established transfer function table and flight-load conditions. However, in actual structural tests, it is often not possible to impose a load in the same position as the point at which the shear load and moment are calculated. For this reason, the actual test-load positions had to be determined and the calculated test loads were redistributed to those positions. Then, the final test load plan was established by applying a whiffle tree to increase the efficiency of the test while also making it easier to apply the actuators. Finally, the suitability of the established test load plan was confirmed by comparison with the flight-load conditions.

The Value of Limited Flexibility in Service Network Designs

Less-than-truckload carriers rely on the consolidation of freight from multiple shippers to achieve economies of scale. Collected freight is routed through a number of transfer terminals at each of which shipments are grouped together for the next leg of their journeys. We study the service network design problem confronted by these carriers. This problem includes determining (1) the number of services (trailers) to operate between each pair of terminals and (2) a load plan, which specifies the sequence of transfer terminals that freight with a given origin and destination will visit. Traditionally, for every terminal and every ultimate destination, a load plan specifies a unique next terminal. We introduce the [Formula: see text]-alt model, which generalizes traditional load plans by allowing decision makers to specify a desired number of next-terminal options for terminal–destination pairs using a vector [Formula: see text]. We compare a number of exact and heuristic approaches for solving a two-stage stochastic variant of the [Formula: see text]-alt model. Using this model, we show that, by explicitly considering demand uncertainty and by merely allowing up to two next-terminal options for terminal–destination pairs in the load plans, carriers can generate substantial cost savings that are comparable to the ones yielded by adopting load plans that allow for any next terminal to be a routing option for terminal–destination pairs. Moreover, by using these more flexible load plans, carriers can generate savings on the order of 10% over traditional load plan designs obtained by deterministic models.

THE BALANCED PRODUCTION LOAD OF A MACHINE-ENGINEERING ORGANIZATION

The article deals with an approach to calculation of equipment, employee or work centers load during the production plan forming by machine engineering organizations. The calculations are based on the duration of manufacturing operations and the electronic structure of items, and provide the most balanced workload at the shortest time of production. The article describes the model of item production and the technique of production plan forming according to each work center with the set of calculation constraints. It also calculates the efficiency of an equipment load and time of production based on the current production plan. The calculation of load plan for work centers is provided by auxiliary software module of an interactive web-resource using the T-SQL.

An Exact Method for Robust Capacity Requirements Planning

This paper proposes a robust method of capacity requirements planning (CRP) that can generate a stable load plan against dynamic changes in a manufacturing environment. In our study, robustness refers to the degree of stability in the load plan for the occurrence of unexpected events. The purpose of the proposed method is to determine the processing periods of operation orders with the aim of minimizing the probability that the resource requirement of each operation order will exceed the capacity of corresponding resources. Through numerical experiments, we demonstrate the effectiveness of the proposed CRP method in terms of its robustness.