American Airlines

About: American Airlines is a company organization based out in Fort Worth, Texas, United States. It is known for research contribution in the topics: Revenue & Inventory control. The organization has 357 authors who have published 286 publications receiving 6138 citations. The organization is also known as: AA & AAL.

The Shifting Bottleneck Procedure for Job Shop Scheduling

Abstract: We describe an approximation method for solving the minimum makespan problem of job shop scheduling. It sequences the machines one by one, successively, taking each time the machine identified as a bottleneck among the machines not yet sequenced. Every time after a new machine is sequenced, all previously established sequences are locally reoptimized. Both the bottleneck identification and the local reoptimization procedures are based on repeatedly solving certain one-machine scheduling problems. Besides this straight version of the Shifting Bottleneck Procedure, we have also implemented a version that applies the procedure to the nodes of a partial search tree. Computational testing shows that our approach yields consistently better results than other procedures discussed in the literature. A high point of our computational testing occurred when the enumerative version of the Shifting Bottleneck Procedure found in a little over five minutes an optimal schedule to a notorious ten machines/ten jobs problem on which many algorithms have been run for hours without finding an optimal solution.

Gender and Ethnicity Differences in Freshmen Engineering Student Attitudes: A Cross-Institutional Study*

Abstract: We examine the attitudes of entering freshman engineering students and how they change over the course of the first year at 17 institutions. In addition to better understanding these attitudes and the changes that occur, we explore how these changes potentially affect such issues as “first term probation” and attrition from engineering programs. Particular attention is directed at isolating differences due to gender and ethnicity. Thirteen different student attitudes were captured using the Pittsburgh Freshman Engineering Attitude Survey© (PFEAS) at the beginning of the first semester (pre) and at either the end of the first semester or first academic year (post). Definite gender differences were found on the pre-survey for five of the attitude measures. For all but one of these measures, female engineering students' initial attitudes were more negative than those of male students. Across the sample of institutions, female students consistently began their engineering studies with a lower confidence in background knowledge about engineering, their abilities to succeed in engineering, and their perceptions of how engineers contribute to society than did their male counterparts. However, those same female students were more comfortable with their study habits than were the male students. The post questionnaire data indicated that differences for three of these five attitude measures persisted. Most important, female engineering students continued to maintain a lower confidence in their abilities to succeed in engineering as compared to male engineering students. When the PFEAS data were mapped into EC 2000 outcomes, comparable cross-institutional gender differences were observed that paralleled those found for the attitudinal measures. Because the number of minority students was relatively small, significant cross-institutional differences between each minority cohort studied (African American, Asian Pacific, and Hispanic) and the majority cohort, similar cross-institutional patterns could not be observed. However, possible trends were found between African American and majority students' attitudes for certain measures, while other attitudinal measures were found to be significant when Hispanic students were compared to majority students. Significant attitudinal differences between Asian Pacific and majority students were similar to those found between female and male engineering students. By knowing how attitudinal measures differ among gender and ethnic cohorts, and understanding how those differences relate to attrition from engineering programs, we can then developed more informed programmatic initiatives that can impact these attitude in a positive manner. As a result, we may be able to reduce engineering attrition, especially by underrepresented student cohorts.

Risk adjusted multicriteria supplier selection models with applications

Abstract: Most manufacturers are continuously seeking their supplier base around the world and look for an opportunity to significantly reduce supply chain costs. Singular emphasis on supply chain cost, however, can make the supply chain brittle and more susceptible to the risk of disruptions. The objective of this paper is to develop multicriteria supplier selection models incorporating supplier risk and apply them to a real company. We develop two different types of risk models, value-at-risk (VaR) and miss-the-target (MtT). We model the risk-adjusted supplier selection problem as a multicriteria optimisation problem and solve it in two phases. Phase 1 is the pre-qualification step, where a large set of initial suppliers is reduced to a smaller set of manageable suppliers using various multi-objective ranking methods. In Phase 2, order quantities are allocated among the short listed suppliers using a multi-objective optimisation model. In the multi-objective formulation, price, lead-time, VaR type risk of disrupt...

Generating and remembering passwords

Abstract: A survey evaluating the generation and use of passwords revealed that students have 8.18 password uses. With 4.45 different passwords to cover these functions, the average password has 1.84 applications. Two thirds of passwords are designed around one's personal characteristics, with most of the remainder relating to relatives, friends or lovers. Proper names and birthdays are the primary information used in constructing passwords, accounting for about half of all password constructions. Almost all respondents reuse passwords, and about two thirds of password uses are duplications. Passwords have been forgotten by a third of respondents, and over half keep a written record of them. We found empirical confirmation of some ‘bad password practices’ discussed in the literature, and provide suggestions for password construction and use. Copyright © 2004 John Wiley & Sons, Ltd.

Preliminary Evaluation of Flight Delay Propagation through an Airline Schedule

Abstract: Airline schedules are based on the carefully-planned use of resources, airports, planes, crews, etc., to provide passengers with on-time arrivals. When airport capacity is reduced below demand, the...