Numerical schemes for the optimal input flow of a supply-chain

An innovative numerical technique is presented to adjust the inflow to a supply chain in order to achieve a desired outflow, reducing the costs of inventory, or the goods timing in warehouses. The supply chain is modelled by a conservation law for the density of processed parts coupled to an ODE for the queue buffer occupancy. The control problem is stated as the minimization of a cost functional J measuring the queue size and the quadratic difference between the outflow and the expected one. The main novelty is the extensive use of generalized tangent vectors to a piecewise constant control, which represent time shifts of discontinuity points. Such method allows convergence results and error estimates for an Upwind- Euler steepest descent algorithm, which is also tested by numerical simulations

Reliability-based economic model predictive control for generalized flow-based networks including actuators' health-aware capabilities

This paper proposes a reliability-based economic model predictive control (MPC) strategy for the management of generalized flow-based networks, integrating some ideas on network service reliability, dynamic safety stock planning, and degradation of equipment health. The proposed strategy is based on a single-layer economic optimisation problem with dynamic constraints, which includes two enhancements with respect to existing approaches. The first enhancement considers chance-constraint programming to compute an optimal inventory replenishment policy based on a desired risk acceptability level, leading to dynamically allocate safety stocks in flow-based networks to satisfy non-stationary flow demands. The second enhancement computes a smart distribution of the control effort and maximises actuators’ availability by estimating their degradation and reliability. The proposed approach is illustrated with an application of water transport networks using the Barcelona network as the considered case study.Peer ReviewedPostprint (author's final draft

Optimal Sizing of Voltage Control Devices for Distribution Circuit with Intermittent Load

We consider joint control of a switchable capacitor and a D-STATCOM for voltage regulation in a distribution circuit with intermittent load. The control problem is formulated as a two-timescale optimal power flow problem with chance constraints, which minimizes power loss while limiting the probability of voltage violations due to fast changes in load. The control problem forms the basis of an optimization problem which determines the sizes of the control devices by minimizing sum of the expected power loss cost and the capital cost. We develop computationally efficient heuristics to solve the optimal sizing problem and implement real-time control. Numerical experiments on a circuit with high-performance computing (HPC) load show that the proposed sizing and control schemes significantly improve the reliability of voltage regulation on the expense of only a moderate increase in cost.Comment: 10 pages, 7 figures, submitted to HICSS'1

APPROACH TO THE FORMING OF RATIONAL TECHNOLOGY FOR THE EXPORT CARGOES DELIVERY IN SUPPLY CHAIN ON THE PRINCIPLES OF CO-MODALITY

In this article, we propose an approach to the forming of rational technology for the export cargoes delivery in the supply chain on the principles of co-modality in the context of effective interaction of delivery participants, which allows reducing the costs of all them through the optimal use of resources related to delivery and increasing the competitive advantages of products. Taking into account the strengthening of cooperation between road and rail transport, under modern conditions, combined transport within the international transport corridor is proposed as an alternative option to promote cargo flow in the supply chain. As a result of experimental studies carried out on the basis of the simulation model of the delivery process in the Petri Nets, the time characteristics of technological processes under alternative schemes depending on the input parameters of the model have been determined. A comparative assessment of alternative delivery schemes based on mathematical models has made it possible to establish that the rational scheme for the delivery of export cargo from Ukraine to Germany via the Pan-European Corridor III is the Rolling Highway technology, which ensures compliance with the cargo owner's requirements for delivery time and cost established by the contract. The proposed approach is recommended as a tool for making managerial decisions when planning and organising the delivery of export cargoes from Ukraine to the EU countries in order to effectively manage supply chains by minimising the cost of delivery and environmental damage.

Aircraft optimization by a system approach: Achievements and trends

Recently emerging methodology for optimal design of aircraft treated as a system of interacting physical phenomena and parts is examined. The methodology is found to coalesce into methods for hierarchic, non-hierarchic, and hybrid systems all dependent on sensitivity analysis. A separate category of methods has also evolved independent of sensitivity analysis, hence suitable for discrete problems. References and numerical applications are cited. Massively parallel computer processing is seen as enabling technology for practical implementation of the methodology