Instructors increase their students' understanding and retention of knowledge by creating more opportunities for active learning. According to cognitive psychologists, instructors should design learning activities according to the type and difficulty of the specific knowledge to be learned. Ten cognitive strategies, related to three types of knowledge, can be used to generate active learning.
In recent years air traffic has dramatically increased without a corresponding development of airports. Therefore, airports' limited capacity causes air traffic congestion and consequent expensive delays. The only strategy that can be applied in the short term with low investments aims at the optimal management of present resources; its principal device is Ground Holding, which consists of delaying an aircraft take off whenever it is foreseen it will not land in time because of congestion. We consider a traffic situation with “multiple connections” or “banking,” i.e., the situation where some flights are assigned a set of “preceding” flights; no “successive” flight can start until all its preceding flights have landed. The problem consists of distributing delays to flights, so as to minimize the total delay cost, by respecting airport capacity, connections, and time constraints imposed by airlines. We construct an integer linear programming model and we solve it to optimality with CPLEX. Because the computation time is too high (hours) for real-world instances, we propose an alternative heuristic algorithm, which shows a very low computation time (seconds) and acceptable errors when tested on 30 realistic instances with strongly diversified data.
The problem of scheduling precedence-constrained task systems characterized by interprocessor communication delays is addressed. It is assumed that task duplication is permitted. The target machine is a homogenous multiprocessor with an unbounded number of processors. The general problem is known to be NP-hard; however, when communication delays are small relative to task execution times, the C.P.M. based approach of Colin and Chrétienne (1991) yields an optimal schedule in polynomial time. Extensions to this method of Colin and Chrétienne are presented here, which allow for polynomial-time optimal schedule generation for certain categories of task systems with arbitrary precedence relations, processing times, and communication delays.
Over the years I have had the opportunity to work in and with different organizations on a variety of management science projects. Most have worked out and some have not. Every one has been a learning experience. I have accumulated some of the rules of thumb that I and other use to carry off projects. You have seen many of these rules before. Still, they bear repeating since they are constantly violated. A detailed overview of the 17 rules follows.
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