In one-machine scheduling, MIP time-indexed formulations are often used to provide very good lower bounds through Lagrangian relaxations. In order to get an improved lower bound, we add valid cuts to a time-indexed formulation and show we still have a Lagrangian relaxation that can be solved as a shortest path in a graph. Two branch-and-bound algorithms are then presented for the earliness-tard...

This paper considers Just-In-Time Job-Shop Scheduling, in which each activity has an earliness and a tardiness cost with respect to a due date. It proposes a constraint programming approach, which includes a novel filtering algorithm and dedicated heuristics. The filtering algorithm uses a machine relaxation to produce a lower bound that can be obtained by solving a Just-In-Time Pert problem. I...

The problem of scheduling groups of jobs on a single machine under the group technology assumption is studied. Jobs of the same group are processed contiguously and a sequence independent setup time precedes the processing of each group. All jobs have a common fixed due date, which can be either unrestrictively large or restrictively small. The objective is to minimize the total weighted earlin...

This paper describes a genetic algorithm approach to the dynamic job shop scheduling problem with jobs arriving continually. Both deterministic and stochastic models of the dynamic problem were investigated. The objective functions examined were weighted flow time, maximum tardiness, weighted tardiness, weighted lateness, weighted number of tardy jobs, and weighted earliness plus weighted tardi...

The problem of determining a schedule of jobs with unit time lengths on a single machine that minimizes the total weighted earliness and tardiness penalties with respect to arbitrary rational due dates is formulated as an integer programming problem We show that if the penalties meet a certain criterion called the Dominance Condition then there exists an extremal optimal solution to the LP rela...

Recent developments in cotton (Gossypium hirsutum L.) production technology in the Delta include drill planting cotton in an ultra-narrow-row (UNR) production system. Ultra-narrow-row cotton is a low-input production system designed to maximize economic returns. The premise is that UNR cotton will be lower yielding, but the reduction in input costs will result in a larger profit margin. Researc...

The just-in-time production philosophy has led to a growing interest in scheduling problems considering both earliness and tardiness penalties. Most publications considering these so-called non-regular objective functions are devoted to single machine problems. In the case of multi-machine problems, there are some papers dealing with parallel machine problems. However, for multi-operation sched...

wheat is a crop with spring and winter types and wide adaptability to different climate conditions. the wide adaptability of wheat is mainly controlled by three groups of genetic factors and among them vernalization (vrn) genes play pivotal role in determining spring and winter types. in this study, 395 iranian wheat landraces were characterized with specific primer pairs designed based on vrn-...