â liquefied natural gas (lng) is the most economical way of transporting natural gas (ng) over long distances. liquefaction of ng by using vapor compression refrigeration system requires high operating and capital cost. due to lack of systematic design methods for multistage refrigeration cycles, the conventional approaches of determining optimal cycle configuration are mostly based on trial-an...

Global optimization for sustainable design and synthesis of a large-scale algae processing network under economic and environmental criteria is addressed. An algae processing network superstructure including 7800 processing routes is proposed. Based on the superstructure, a multiobjective mixed-integer nonlinear programming (MINLP) model is developed to simultaneously optimize the unit cost and...

This paper focuses on the collision-free coordination of multiple robots with kinodynamic constraints along specified paths. We present an approach to generate continuous velocity profiles for multiple robots; these velocity profiles satisfy the dynamics constraints, avoid collisions, and minimize the completion time. The approach, which combines techniques from optimal control and mathematical...

We give a short introduction to mixed-integer nonlinear programming from a linear programming perspective. In this approach, all nonlinearities are approximated by linear inequalities and spatial branching, such that in the end only linear programs remain that can be solved efficiently. We present two transportation applications from rather different fields: Railway freight on one side, and nat...

We present a method, based on formulation symmetry, for generating Mixed-Integer Linear Programming (MILP) relaxations with fewer variables than the original symmetric MILP. Our technique also extends to convex MINLP, and some nonconvex MINLP with a special structure. We showcase the effectiveness of our relaxation when embedded in a decomposition method applied to two important applications (m...

Because the purchasing department can play a key role in cost reduction, supplier selection and order allocation are the most important functions of purchasing management. In view of its complexity, it will be focused especially on the final selection stage that consists of determining the best mixture of suppliers and allocating orders among them so as to satisfy different purchasing requireme...

This paper presents scaled quadratic cuts based on scaling the second-order Taylor expansion terms for the decomposition methods Outer Approximation (OA) and Partial Surrogate Cuts (PSC) used for solving convex Mixed Integer Nonlinear Programing (MINLP). The scaled quadratic cut is proved to be a stricter and tighter underestimation for the convex nonlinear functions than the classical supporti...

In the downstream oil & chemical industry Planning and Scheduling are resource intensive, complex, rolling processes. Decisions are taken at different stages within the supply chain (Supply, Manufacturing & Distribution) and at different levels in the management hierarchy (Planning, Scheduling & Operations). They differ in business scope, time horizon & resolution, data certainty & accuracy, pr...

In this study, a flexible optimization approach is introduced to design an optimal biocompatible solvent for an extractive fermentation process with cell-recycling. The optimal process/solvent design problem is formulated as a mixed-integer nonlinear programming model in which performance requirements of the compounds are reflected in the objectives and the constraints. A flexible or fuzzy opti...

In this paper a new approach using Harmony Search (HS) algorithm is presented for placing Distributed Generators (DGs) in radial distribution systems. HS is used for multiple objective planning, to evaluate the DG placement and sizing by considering the power losses and voltage profile as objective functions. HS is operated on 12bus, 15-bus and 33-bus radial distribution system(RDS). Obtained r...