CREATING SUNS ON EARTH

Concerns about climate change and energy security have prompted some countries to revive dormant nuclear fission power programs to meet growing energy demands and reduce carbon dioxide emissions. However, this so-called nuclear renaissance based on fission would have major drawbacks in the areas of safety, security, and nonproliferation. Nuclear fusion, however, is portrayed by its proponents as mitigating these drawbacks, and scientists continue to pursue fusion's promise with two large-scale projects: the International Thermonuclear Experimental Reactor (ITER), and the Laser Inertial Fusion Engine (LIFE) reactor. Although supporters often hail fusion as proliferation resistant, the technology could be used to create weapons-usable fissile material. This article explains how fissile material could be created in ITER or LIFE and analyzes other nonproliferation implications of fusion; the authors discuss the various challenges faced by ITER and LIFE.     

Developing production schedules which balance part usage and smooth production loads for just-in-time production systems

A mixed-model multilevel manufacturing facility running under a just-in-time (JIT) production system is controlled by setting the production schedule for the highest level in the facility, which is usually a mixed-model final assembly line. The schedule is set to achieve the goals of the organization, which under JIT are (1) to keep a constant rate of part usage, and (2) to maintain a smooth production load. In this article we extend earlier work in the literature, which focused on the first goal, by developing scheduling procedures which satisfy both goals. Properties of the resulting production schedules are analyzed and illustrative examples are presented.     

Interactive optimization methodology for fleet scheduling

This article addresses the problem of scheduling the United States Navy's Atlantic Fleet to satisfy overseas strategic requirements. An integer programming formulation is developed but results in a model with prohibitive size. This fact and the qualitative nature of additional secondary objectives and constraints suggest an interactive optimization approach. A system that solves a natural relaxation of the integer program within an interactive environment is discussed.     

A finiteness proof for modified dantzig cuts in integer programming

Let be a basic solution to the linear programming problem subject to: where R is the index set associated with the nonbasic variables. If all of the variables are constrained to be nonnegative integers and x_u is not an integer in the basic solution, the linear constraint is implied. We prove that including these “cuts” in a specified way yields a finite dual simplex algorithm for the pure integer programming problem. The relation of these modified Dantzig cuts to Gomory cuts is discussed.