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Peer Assisted learning (PAL) in-class is well-established and flourishing in higher education across the globe; nevertheless, interest is growing in online versions and is reflected by a number of pilot schemes. These programs have responded to perceived and actual needs of students and institutions; they have explored the available software packages and have begun to create a bank of learning through academic publications, institutional reports, evaluations, and SINET listserv discussions. This paper examines existing online PAL practice from Australia, Canada, the UK and the USA, and focuses on synchronous modes. We discuss (a) the context, mode, and scope of online PAL, and (b) implementation considerations. Despite some "teething problems" of these pilots we are convinced by the early and so far limited explorations highlighted here that online PAL can make a significant contribution to learners in higher education by improving engagement through the flexibility afforded by the online space.

Planning is an important phase of teaching, during which teachers make decisions about various aspects of instruction that ultimately shape students' opportunities to learn. Prior research on teacher planning, however, fails to adequately describe experienced teachers' planning decisions, and is unclear about the extent to which teachers use curriculum materials to inform their decisions. Using data from 6th grade mathematics teachers' use of curriculum materials, this study presents a discipline-specific model of experienced mathematics teachers' planning. The proposed model provides a lens for understanding the nature of teachers' planning decisions, and the conditions under which such decisions change over time. (Contains 1 figure and 1 table.)

Research problem: High turnover rates in long-term nursing facilities exacerbate the existing shortage of caregivers, a trend that will only worsen as the population of the United States ages. Part-time certified nursing assistants (CNAs) provide a significant amount of patient care in these facilities. CNAs also have high annual rates of turnover, which can harm health outcomes and increase the cost of care. In this study, we empirically analyze the effect of scheduling decisions on part-time CNA turnover. We explore three research questions that examine both how much and with whom a CNA is scheduled to work. We seek to empirically answer how (1) hours worked and (2) coworker variability influence turnover for part-time CNAs and if (3) coworker variability moderates the relationship between hours worked and CNA turnover. Methodology/results: Using novel data from one of the nation's largest nursing home organizations, which includes data for 6,221 part-time CNAs at 157 facilities in the United States over a 26-month period, we identify two scheduling levers managers may be able to use to influence turnover. As hours worked increase, turnover first decreases and then increases, demonstrating a nonlinear U-shaped relationship between hours worked and turnover. We also find that high coworker variability increases turnover while also moderating the effects of hours worked on turnover. In post hoc analyses, we demonstrate that high CNA turnover has negative impacts on patient health. Managerial implications: These findings suggest that managers may be able to leverage part-time CNA scheduling to reduce turnover, improving both the quality and cost of care. Specifically, we demonstrate that managers can reduce CNA turnover by increasing hours worked, scheduling coworkers together consistently and doing both simultaneously. Supplemental Material: The online appendices are available at https://doi.org/10.1287/msom.2021.0533. [ABSTRACT FROM AUTHOR]

Scheduling Advertising on Cable Television Advertisement scheduling is a daily essential operational process in the television business. Efficient distribution of viewers among advertisers allows the television network to satisfy contracts and increase ad sale revenues. Ad scheduling is a challenging multiperiod, mixed-integer programming problem in which the network must create schedules to meet advertisers' campaign goals and maximize ad revenues. Each campaign must meet a specific target group of viewers and a unique set of constraints. Moreover, the number of viewers is uncertain. To solve this problem, S. Souyris, S. Seshadri, and S. Subramanian develop and implement a practical approach that combines mathematical programming and machine learning to create daily schedules. According to standard business metrics and the small integer programming gap, these schedules are of high quality. Using their methods, leading networks in the United States and India experience a 3% to 5% revenue increase, which translates to about $60 million annually for one prominent user. Advertisement scheduling is a daily essential operational process in the television business. Efficient distribution of viewers among advertisers allows the television network to satisfy contracts and increase ad sale revenues. Ad scheduling is a challenging multiperiod, mixed-integer programming problem in which the network must create schedules to meet advertisers' campaign goals and maximize ad revenues. Each campaign must meet a specific target group of viewers and a unique set of constraints. Moreover, the number of viewers is uncertain. To solve this problem, we develop and implement a practical approach that combines mathematical programming and machine learning to create daily schedules. These schedules are of high quality according to standard business metrics and the small integer programming gap. Leading networks in the United States and India using our methods experience a 3%–5% revenue increase. Supplemental Material: The e-companion is available at https://doi.org/10.1287/opre.2022.2430. [ABSTRACT FROM AUTHOR]

• Twelve University of Dayton air handler units (AHUs) in five buildings were analyzed for potential energy savings. • Eleven AHUs were over-pressurized; reducing their static pressure resulted in 33% fan energy savings. • Nine AHUs served unoccupied zones overnight; scheduling them off resulted in 35% fan energy savings. • All economizers were identified as fully or partially malfunctioning; fixing their controls could result in 17% cooling savings. With heating, ventilation, and air conditioning (HVAC) consuming the largest share of commercial building energy usage in the U.S., identifying HVAC energy efficiency measures can have a large impact. Thus, this research provides results from a University of Dayton case study of twelve total air handling units (AHUs) in five diverse buildings – academic, athletics, administrative, place of worship, and library – that were analyzed for energy savings through three energy efficiency measures: reducing AHU static pressure (SP), scheduling AHUs off overnight, and identifying and fixing economizer controls. First, variable air volume (VAV) damper position distributions were created to identify over-pressurized AHUs and step down their SP accordingly. Eleven of the twelve AHUs were determined to be over-pressurized and lowering their SP to final setpoints ranging 0.8 – 1.2 inches water-gauge resulted in average fan energy savings of 33%. Next, nine of the twelve AHUs were found to be serving unoccupied zones overnight and were in turn scheduled off for seven to twelve hours per night depending on building usage, resulting in 35% average energy savings. Lastly, AHU fraction outdoor air was calculated and compared to ideal economizer fraction outdoor control. All economizers were identified as fully or partially malfunctioning and if fixed could result in an average of 17% cooling savings. [ABSTRACT FROM AUTHOR]

Outpatient services account for more than four-fifths of patient care in the United States, and most patients access these services via appointment scheduling. Because of the possibility of patient no-shows, healthcare providers usually rely on overbooking. If very few patients show up, it will leave hospital resources underutilized, whereas too many showing up will increase patient wait times and increase staff overtime costs. In a hospital or a network of clinics, where patients could enter and exit at various stations and have complex flow patterns, scheduling becomes even more of a challenge. In "Coordinated Patient Appointment Scheduling for a Multistation Healthcare Network," D. Wang, K. Muthuraman, and D. Morrice propose a multistation network model that carefully strikes a balance between assumptions that allow tractability and assumptions that disallow real-world adoption. Given the complexity involved in solving the model, they explore a sequence of approximations and find one that offers a significant computational advantage. Current healthcare reforms advocate significantly to improve the coordination of services around a patient-centric model. With most patient care delivered through outpatient services, the need to coordinate scheduling between different services in a hospital or colocated clinics becomes central to successful reform. Currently, outpatient services require independent appointment decisions, and the coordination is left to the patient. This approach causes several inefficiencies, including an increase in missed appointments and unacceptable access delays. This paper proposes a multistation network model that carefully strikes a balance between assumptions that allow tractability and assumptions that disallow real-world adoption. To allow for real-world applicability, we consider sequential appointment scheduling in a network of stations with exponential service times, no-show possibilities, and overbooking. We argue and present evidence that a heuristic myopic scheduling policy is close to optimal. However, because it is not simple enough for practical implementation, we explore a sequence of approximations and find one that offers a significant computational advantage. We also provide several managerial insights and discuss how network structures affect complexity. [ABSTRACT FROM AUTHOR]

The general agreement on the desirability of "full employment" often obscures the very real disagreement over the meaning to be attached to that term. Critics of the Census measure of unemployment have long charged that this measure seriously understates the extent of unemployment, particularly during periods of recession and depression. The authors of this article propose a new measure of "labor slack," or the underutilization of the potential labor force, which they believe would effectively complement the present Census measure in providing policy makers with the information needed to implement the Full Employment Act. [ABSTRACT FROM AUTHOR]

This article discusses the value of an executive's time and the importance of proper time management. The authors note that an executive's time is an important resource and plays a significant role in the planning of an organization's activities. The authors examine time management literature and attempt to develop an easy to understand process for learning how to effectively and efficiently manage time. They present ten principals that outline the entire process of time management including planning, analysis, budgeting, flexibility, implementation and segmentation.

Airlines use robust scheduling to mitigate the impact of unforeseeable disruptions on profits. We examine how effectively three common practices-flexibility to swap aircraft, flexibility to reassign gates, and scheduled aircraft downtime-accomplish this goal. We first estimate a multiple-input, multiple-outcome production frontier, which defines the attainable set of outcomes from given inputs. We then recover unobserved input costs and calculate how expenditure on inputs affects outcomes and revenues. We find that the per-dollar return from expenditure on gates, or more effective management of existing gate capacity, is three times larger than the per-dollar returns from other inputs. Next, we use the estimated trade-offs faced by carriers along the frontier to measure the value to carriers of reducing delays. Finally, we calculate the improvement in carriers' outcomes and profits if their operational inefficiencies are eliminated. On average, we estimate that operational inefficiencies cost carriers about $1.7 billion in revenue annually. This paper was accepted by Serguei Netessine, operations management. [ABSTRACT FROM AUTHOR]

• Time spent at home increased 1.2–1.9 h per day during the pandemic. • 1-member households spent less time at home. • 2 + member households spent more time at home. • Office and kitchen space usage increased during the pandemic. • Changes to occupancy have strong implications on home energy use. Many aspects of the daily lives of those living in the United States were substantially impacted by the COVID-19 pandemic in the year 2020. A broad diversity of measures was implemented to curb the spread of the virus, many of which included adjustments to where and how people worked, went to school, and otherwise conducted their daily lives compared to pre-pandemic times. This has impacted how residential buildings are used, how much time people spend in their homes, and as a result, how much energy these buildings consume. The main objective of this study is to analyze, at a national scale, the differences in the occupancy schedules and activities conducted in homes in the U.S., as compared to pre-pandemic. 15 years of American Time Use Survey and Current Population Survey data, from 2006 to 2020, was used in this study to analyze the occupancy schedules for both pandemic (2020) and pre-pandemic (2006–2019) times. These impacts were also analyzed with respect to variables including, weekday/weekend, month of the year, age of the occupants, household income, and household size. The impact of the pandemic on occupant schedules were most substantial in the initial months, whereas as the months progressed, these occupancy profiles slowly changed. Across 2020, people spent, on average, 8 % more time (1.9 h) in their home on weekdays, and 3–6 % (1.2 h) on weekend days. The percentage of time spent for different activities and locations within homes were also studied. For 1-member households, their time spent at home decreased whereas for 2-, 3-, and 4- member households, they spent more time at home. Overall, people spent around 45% more time doing office- and work-related activities at home compared to pre-pandemic, which is likely due to increased remote working and schooling. This research helps to improve the understanding of the occupancy presence and absence profiles in U.S. residential buildings due to the pandemic and provides new insights as to modified profiles for researchers, building designers, and policy makers. [ABSTRACT FROM AUTHOR]

An examination timetabling problem at a large American university is presented. Although there are some important differences, the solution approach is based on the ITC 2007 winning solver which is integrated in the open source university timetabling system UniTime. In this work, nine real world benchmark data sets are made publicly available and the results on four of them are presented in this paper. A new approach to further decreasing the number of student conflicts by allowing some exams to be split into multiple examination periods is also studied. [ABSTRACT FROM AUTHOR]

The National Science Foundation provides funding for scientific research throughout the United States. Its program directors solicit requests for funding through calls for proposals and then assemble panels of experts to review these requests. The program directors are responsible for reserving meeting rooms for each of the panels. Our work automates much of the room reservation process by constructing and solving an optimization model that determines how panels should be assigned to available rooms to maximize the utilization of available meeting rooms. The model accommodates multiday panels, differences between the rooms (e.g., capacity, projector support), and double-booking constraints for both rooms and panel organizers. Staff members at the National Science Foundation are currently using this software, and have employed it to successfully schedule engineering directorate panels for the 2014–2015 review year. [ABSTRACT FROM AUTHOR]

Few projects have had such a profound and lasting effect on the world as the Manhattan Project. Today, after it was approved 70 years ago by President Franklin D. Roosevelt, its legacy is felt in nuclear medicine, military defence, terrorist threats, and the production of energy. What was remarkable about this project was that to succeed it had to push through the frontiers of knowledge in ways that are impressive even by today's standards. This paper includes a short history of the project and the challenges that had to be overcome. But the paper is primarily about a very large organisation that was forced to learn quickly, compress each stage in the project in a race against time, and pass knowledge, which was often incomplete, from one phase to the next. As such, it makes a theoretical contribution to the literature on the management of large-scale science projects and provides insight into the problems that these projects face today. [ABSTRACT FROM AUTHOR]

Income tax systems in some countries follow primarily schedular models that classify income by type, match it with deductions from the same class, and compute a separate tax on each class. The United States income tax uses a global tax model under which it taxes citizens and permanent residents on their worldwide income without regard to source or character. The United States system is not purely global but includes schedular elements. This Article exposes embedded schedularity in the United States income tax in the three principal areas of investment income, personal services income, and tax free income. The Article tests whether that schedularity enhances or undercuts the tax principles of horizontal and vertical equity that underlie the development of both global and schedular tax systems in advanced economies. Horizontal equity is a straightforward principle and seems an indisputable precept. It requires that like taxpayers incur like tax burdens. The principle of vertical equity is more nuanced and departs from the principle that as one's income increases, one can and should contribute ever larger percentages of that income to supporting governmental services. Vertical equity assumes that the wealthier one is, the less likely it is that an increased tax burden will diminish the individual's welfare in any material way. Conversely, the less wealthy one is, the more likely it is that an increased tax burden will diminish the individual's welfare materially. The vertical equity principle led to the development of the progressive rate structures. While the Article observes that Congress uses schedular elements to accomplish distributional policy goals, initially in order to protect progressivity, more recently schedularity has tended to increase overall regressivity in taxation. The Article concludes that United States taxation seems to be moderately schedular and that schedularity in the United States contributes to regressivity in taxation. [ABSTRACT FROM AUTHOR]

A system was developed to efficiently schedule aircraft into congested resources over long ranges and present that schedule as a decision support system. The scheduling system consists of a distributed network of independent schedulers, loosely coupled by sharing capacity information. This loose coupling insulates the schedules from uncertainty in long-distance estimations of arrival times, while allowing precise short-term schedules to be constructed. This 'rate profile' mechanism allows feasible schedules to be produced over long ranges, essentially constructing precise short-range schedules that also ensure that future scheduling problems are solvable while meeting operational constraints. The system was tested operationally and demonstrated reduced airborne delay and improved coordination. [ABSTRACT FROM AUTHOR]

The U.S. truck driver scheduling problem (US-TDSP) is the problem of visiting a sequence of λ locations within given time windows in such a way that driving and working activities of truck drivers comply with U.S. hours-of-service regulations. In the case of single time windows it is known that the US-TDSP can be solved in O(λ³) time. In this paper, we present a scheduling method for the US-TDSP that solves the single time window problem in Oλ²) time. We show that in the case of multiple time windows the same complexity can be achieved if the gap between subsequent time windows is at least 10 hours. This situation occurs, for example, if, because of opening hours of docks, handling operations can only be performed between 8.00 a.m. and 10.00 p.m. Furthermore, we empirically show that for a wide range of other problem instances the computational effort is not much higher if multiple time windows are considered. [ABSTRACT FROM AUTHOR]

The scheduling needs of umpires and referees differ from the needs of sports teams. In some sports leagues, such as Major League Baseball in the United States, umpires travel throughout the league's territory; they do not have a "home base." For such leagues, balancing the need to minimize umpire travel and the objective that an umpire should not handle the games of a particular team too frequently is important. We have used our approach, which is based on network optimization and simulated annealing, to successfully schedule Major League Baseball umpires. To develop this approach, we created the traveling umpire problem, which includes the major umpire scheduling issues and also provides a test bed for alternative techniques. [ABSTRACT FROM AUTHOR]

There are many benefits of building information modeling (BIM) to the construction industry when compared to the traditional approach to design and construction. To properly prepare students, many schools are introducing BIM in their coursework as a response to the current and future needs of the construction industry. The aim of this research was to evaluate the current implementation of BIM and to identify trends in the teaching of BIM in architecture and construction academic programs. A survey that investigated the implementation of BIM into accredited programs in architecture and construction education was sent to architecture and construction schools in the U.S. The survey results indicated that most architecture and construction schools either have an interest in or have already implemented BIM into their curriculum. The majority of the schools expected students to have a basic knowledge of BIM upon graduation; perceived BIM as important to industry; and planned to fully integrate BIM into their curriculum. The results show that more architecture than construction schools have implemented BIM into their curriculum. Construction schools were more likely to use four-dimensional (4D) and five-dimensional (5D) models in teaching construction scheduling and estimating when compared to architecture schools. [ABSTRACT FROM PUBLISHER]

This paper presents the results of a study that incorporates computer simulations in teaching linear scheduling concepts and techniques, in a civil engineering course, 'Construction Planning and Scheduling.' The effect of the use of computer simulations in the course shows that the students who were taught with simulation gained a better understanding of linear scheduling concepts and techniques than those students taught without simulation. The data and analysis leading to this finding are presented and discussed in this paper. Two groups of students were considered in this research: (1) civil engineering students from the Department of Civil and Coastal Engineering at the University of Florida and (2) civil engineering students from the Department of Civil Engineering at the University of Chile. Each group was randomly separated into two subgroups: one subgroup was taught by using the traditional method of linear scheduling (without the use of computer simulation) and the other subgroup was taught by using simulations. At the end of the teaching period, the students in both subgroups answered an objective test-type questionnaire specifically designed to address their understanding of linear scheduling techniques. They were also required, in a more subjective way, to provide their evaluation of the teaching method involved. To assess the effect of incorporating computer simulation in teaching linear scheduling, the students' evaluations and answers to the questionnaire were statistically compared. The analysis of the responses showed significant differences between the students' understanding of the subject by using the two teaching methods, with the use of computer simulation shown to be a more effective teaching tool for linear scheduling techniques. [ABSTRACT FROM AUTHOR]

We study a supply chain scheduling problem, where a common due date is assigned to all jobs and the number of jobs in delivery batches is constrained by the batch size. Our goal is to minimize the sum of the weighted number of tardy jobs, the due-date-assignment costs and the batch-delivery costs. We show that some well-known $\mathcal{NP}$-hard problems reduce to our problem. Then we propose a pseudo-polynomial algorithm for the problem, establishing that it is $\mathcal{NP}$-hard only in the ordinary sense. Finally, we convert the algorithm into an efficient fully polynomial time approximation scheme. [ABSTRACT FROM AUTHOR]

To improve coverage against vaccine-preventable diseases for children and adults, and to aid caretakers and providers in making appropriate and timely vaccination decisions, Georgia Institute of Technology collaborated with the Centers for Disease Control and Prevention to develop decision support tools for creating optimized catch-up immunization schedules for four target groups: children through age 6, adolescents ages 7 through 18, adults ages 19 and over in the United States, and children and adolescents through age 19 in Canada. Our solution to the catch-up scheduling problem for each targeted group determines the best coverage schedule for each individual given his (her) vaccination history and age. If an individual misses one or more doses of a recommended vaccine, a health-care professional is typically responsible for generating a feasible catch-up schedule that optimizes the person's coverage against vaccine-preventable diseases, a task that is often challenging and time consuming. Inappropriate schedules could prevent some individuals from being vaccinated in a timely manner, potentially increasing their risk of contracting a disease. Each decision support tool uses a dynamic programming algorithm to construct recommended immunization schedules in an optimized manner. These tools simplify the tedious process of manually constructing immunization schedules, expedite the process, and eliminate errors. [ABSTRACT FROM AUTHOR]

The current study draws on national data to explore differences in access to flexible work scheduling by the gender composition of women's and men's occupations. Results show that those who work in integrated occupations are more likely to have access to flexible scheduling. Women and men do not take jobs with lower pay in return for greater access to flexibility. Instead, jobs with higher pay offer greater flexibility. Integrated occupations tend to offer the greatest access to flexible scheduling because of their structural locations. Part-time work is negatively associated with men's access to flexible scheduling but positively associated with women's access. Women have greater flexibility when they work for large establishments, whereas men have greater flexibility when they work for small establishments. [ABSTRACT FROM AUTHOR]

In the United States, public television claims itself a champion of localism. A prime-time schedule analysis of the Public Broadcasting Service's (PBS) member stations establishes localism scores, and discriminant analysis finds variables that predict differences among stations. Market level variables (income, education, ethnic diversity, geographic component) and organizational level variables (Community Service Grants, membership funding, overall revenue) affect localization of member stations' schedules. This is the first empirical study utilizing a structural operationalization of localism, inclusive of all programming genres, applied to PBS member stations. [ABSTRACT FROM AUTHOR]

Healthcare currently consumes 17% of the U.S. Gross Domestic Product and is expected to reach 20% within the coming decade. Confronted with such high costs, sharp demand, and limited capacity, many hospitals now are vying for shorter lengths of stay and are transferring services from inpatient to outpatient facilities. This paper seeks to develop a methodology for constructing effective outpatient appointment scheduling systems. The objective of these appointment systems is to minimize the average total cost function describing total costs incurred by patient waiting and by staff idle time and overtime. In the paper, we will establish that the average total cost function exhibits a unimodal curve. The lowest point of the curve essentially means the lowest average total cost. We will next develop a simulation-based heuristic algorithm for finding an outpatient schedule near the lowest point. In the paper, we present numerical examples using the heuristic based upon a set of predetermined unit costs. Specifically, we find the near optimal interappointment times for schedules, where there are two and three patients in each block, respectively. The current work does not consider possible no shows and walk-ins. Future work will undertake these issues. [ABSTRACT FROM AUTHOR]

Scheduling term-end exams ( TEE) at the United States Military Academy in West Point is unlike any other exam timetabling problem we know of. Exam timetabling normally produces a conflict-free timetable covering a reasonably long exam period, where every exam is scheduled exactly once for all the students enrolled in the corresponding class. The situation is quite different at West Point. There are hundreds of exams to schedule over such a short time period that there is simply no feasible solution. The challenge is then to allow something that is not even considered elsewhere, that is, creating multiple sessions of some exams, scheduled at different times within the exam period, to allow each student to take all exams he/she must take. The overall objective is to find a feasible exam schedule with a minimum number of such duplicate exams. The paper describes a system that has been developed at GAMS Development Corp. in close cooperation with the scheduling staff at West Point, and that has been used successfully since 2001. It uses mathematical optimization in several modules, and some of the techniques proposed are new. It is fast and flexible, and allows for human interaction, such as adding initially unexpected constraints, coming for instance from instructors’ preferences and dislikes, as well as their hierarchical rankings. It is robust and can be used by people familiar with the organization at West Point, without the need for them to be technically-trained. Overall, using the course and student information databases, it is an effective decision support system that calls optimization tools in an unobtrusive way. [ABSTRACT FROM AUTHOR]

Abstract: This study explores the relation between airline market structure and schedule differentiation. Using a location theory framework applied to product differentiation over the time scale, the analysis relates the level of competition, and the presence of low-cost carriers in non-stop US markets to schedule clustering. As expected from theory, it is found that schedule clustering increases with competition, resulting in reduction in product differentiation. It is also found that this tendency is lower in the presence of low-cost carriers and when there is a strong hub effect where dominant hub airline own, rather than compete with their feeder subsidiaries. [Copyright &y& Elsevier]

Abstract: The development of new system capabilities typically depends upon the prior success of advanced technology research and development efforts. These systems developments inevitably face the three major challenges of any project: performance, schedule and budget. Done well, advanced technology programs can substantially reduce the uncertainty in all three of these dimensions of project management. Done poorly, or not at all, and new system developments suffer from cost overruns, schedule delays and the steady erosion of initial performance objectives. It is often critical for senior management to be able to determine which of these two paths is more likely—and to respond accordingly. The challenge for system and technology managers is to be able to make clear, well-documented assessments of technology readiness and risks, and to do so at key points in the life cycle of the program. In the mid 1970s, the National Aeronautics and Space Administration (NASA) introduced the concept of “technology readiness levels” (TRLs) as a discipline-independent, programmatic figure of merit (FOM) to allow more effective assessment of, and communication regarding the maturity of new technologies. In 1995, the TRL scale was further strengthened by the articulation of the first definitions of each level, along with examples (J. Mankins, Technology readiness levels, A White Paper, NASA, Washington, DC, 1995. ). Since then, TRLs have been embraced by the U.S. Congress’ General Accountability Office (GAO), adopted by the U.S. Department of Defense (DOD), and are being considered for use by numerous other organizations. Overall, the TRLs have proved to be highly effective in communicating the status of new technologies among sometimes diverse organizations. This paper will review the concept of “technology readiness assessments”, and provide a retrospective on the history of “TRLs” during the past 30 years. The paper will conclude with observations concerning prospective future directions for the important discipline of technology readiness assessments. [Copyright &y& Elsevier]

Demand stochasticity is a major challenge for the airlines in their quest to produce profit maximizing schedules. Even with an optimized schedule, many flights on departure have empty seats while others suffer a lack of seats to accommodate passengers who desire to travel. We approach this challenge, recognizing that demand forecast quality for a particular departure date improves as it approaches, by developing a dynamic scheduling approach that reoptimizes elements of the flight schedule during the passenger booking process. The goal is to match capacity to demand given the many operational constraints that restrict possible assignments. We leverage flight retiming as a new dynamic scheduling mechanism and develop a reoptimization model that integrates both flight retiming and refleeting. Our reoptimization approach, redesigning the flight schedule at regular intervals, uses information from both revealed booking data and improved forecasts available at later reoptimizations. We conduct experiments using data from a major U.S. airline and demonstrate that significant potential profitability improvements are achieved. [ABSTRACT FROM AUTHOR]

Water is the lifeblood of the American West and the foundation of its economy, but it remains its scarcest resource. The explosive population growth in western United States, the emerging additional need for water for environmental uses, and the national importance of the domestic food production are driving major conflicts between these competing water uses. The case of the Middle Rio Grande illustrates the problem very well. The river is the ecological backbone of the Chihuahuan Desert region in the western United States, and supports its dynamic and diverse ecology, including the fish and wildlife habitat. The Rio Grande Silvery Minnow is federally listed as an endangered species, and the irrigated agriculture in the Middle Rio Grande has come under increasing pressure to reduce its water consumption and maintain the desired level of service to its water users. This paper will present the writers ongoing research on options to make irrigation system operations more efficient in the Middle Rio Grande Conservancy District (MRGCD). Specifically, it will describe formulation and implementation of a decision support system (DSS) that can assist the MRGCD managers to more efficiently plan and implement their water delivery operations, thereby reducing river diversions. The MRGCD DSS uses linear programming to find an optimum water delivery schedule for canal service areas in the MRGCD irrigation system. The computer model is presently formulated along with the related data sets for two of the four divisions in the MRGCD. For the past 3 years, the model has been validated in the field and the evaluation indicates that the model recommendations are realistic and represent current management practices. The future plans are to complete the data files for the irrigation networks in the remaining two divisions and concurrently help the MRGCD implement the DSS to guide water delivery operation. [ABSTRACT FROM AUTHOR]

As air traffic in the United States has grown over the last several years, traffic demand has begun to outstrip capacity. As of 2005, the Federal Aviation Administration (FAA) had no effective approach for strategically managing a weather event that has been very disruptive to the national aviation system--large-scale thunderstorms that block the major flight routes in the northeastern United States. The operations research team that supports the FAA's efforts to provide innovations in air traffic management, led by researchers at Metron Aviation, Inc. and the Volpe Transportation Center, recognized the consequence of this operational deficiency and set out to resolve it. In this paper, we show how this team (1) developed and applied system-simulation models to quantify the extent of the traffic flow management problem and convey its magnitude to the FAA and to the aviation industry; (2) designed the Airspace Flow Program (AFP), a new approach to managing air traffic that could correct the problem within the limitations of a short development cycle and a change-resistant culture; (3) designed and developed an interactive simulation system that could be and was used to refine and perfect this concept prior to deployment by developing policies on the use of a decision support system; (4) engaged FAA and airline traffic management experts in a series of interactive exercises using the simulation system to develop the final software design, operational procedures, and decision rules for deployment and use; and (5) provided a clear and convincing postdeployment benefits assessment for the new traffic management approach. The deployment of this new capability was an enormous success that both the FAA and the airline community heralded widely. The postdeployment impact assessment showed benefits to the aircraft operators and the flying public of almost $190 million in 2006 and 2007, the first two years of use, compared to less than $5 million in design and development costs. Broader usage of AFPs and new applications for them show a projected 10-year benefit of approximately $2.8 billion. [ABSTRACT FROM AUTHOR]

The article discusses problems that arose with the deployment of software agents (Travel Elves) to handle travel accommodations at the travel office of the Defense Advanced Research Projects Agency (DARPA). Although promising at first, several problems eventually emerged. Three significant sources of error were inconsistent, unavailable, or unreliable data sources, an inability to determine precisely what the Elves should do under various circumstances, and failure to anticipate how properly functioning Elves could sometimes produce unexpected or annoying results.

Within the past three decades, a number of schools and districts, particularly those in rural areas, have moved toward a four-day school week. Recent articles and reports indicate that there are now schools with four-day weeks in Colorado, Wyoming, South Dakota, Louisiana, New Mexico, Idaho, and Nebraska. The reasons for this shift include saving money in the face of declining enrollments and avoiding interruptions and absences due to sports and activities. Districts contemplating the four-day week need current information about this alternative schedule and how it is working in schools around the country. This report is intended to summarize recent research and other articles on the four-day week and make recommendations to district personnel on whether and how it should be implemented. [ABSTRACT FROM AUTHOR]

The article discusses several key issues in designing coscheduling algorithms for clusters in the U.S. The availability of high bandwidth and low-latency networks supported by efficient user-level communication protocols has made high performance computing clusters an attractive and cost effective alternative to traditional multiprocessor systems. These clusters are often used either as dedicated Beowulf systems for running real-world parallel simulations systems for running parallel jobs. The experimental results show that the blocking-based coscheduling scheme has better tolerance to system workload variation compared with the spin-based schemes and overall the blocking-based coscheduling scheme seems a better choice for non-dedicated Linux clusters.

The article discusses the problem of optimal distribution of computational tasks on a network of heterogeneous computers in the U.S. A functional performance model of heterogeneous processors that integrates many essential features of a network of heterogeneous computers having a major impact on its performance such as the processor heterogeneity, the heterogeneity of memory structure and the effects of paging was proposed. A number of algorithms of parallel solution of scientific and engineering problems on heterogeneous networks of computers have been designed and implemented. Under this model, the speed of each processor is represented by a continuous function of the size of the problem whereas traditional models use single numbers to represent the speeds of the processors.

BACKGROUND: Work hour regulations for house staff were intended in part to improve resident clinical and educational performance. OBJECTIVE: To characterize the effect of work hour regulation on internal medicine resident inpatient clinical experience and didactic education. DESIGN: Cross-sectional mall survey. PARTICIPANTS: Chief residents at all accredited U.S. internal medicine residency, programs outside New York. MEASUREMENTS AND MAIN RESULTS: The response rate was 62% (202/324). Most programs (72%) reported no change in average patient load per intern after work hour regulation. Many programs (48%) redistributed house staff admissions through the call cycle. The number of admissions per intern on long can (the day interns have the most admitting responsibility) decreased in 31% of programs, and the number of admissions on other days increased in 21% of programs. Residents on outpatient rotations were given new ward responsibilities in 36% of programs. Third-year resident ward and float time increased in 34% of programs, while third-year elective time decreased in 22% of programs. The mean weekly hours allotted to educational activities did not change significantly (12.7 vs 12.4. P=. 12). but 56% of programs reported a decrease in intern attendance at educational activities. CONCLUSIONS: In response to work hour regulation, many internal medicine programs redistributed rather than reduced residents' inpatient clinical experience. Hours allotted to educational activities did not change: however, most programs saw a decrease in intern attendance at conferences, and many reduced third-year elective time. [ABSTRACT FROM AUTHOR]

In this paper, we propose a generic library of problem-solving methods for scheduling applications. Although some attempts have been made in the past at developing the libraries of scheduling problem-solvers, these only provide limited coverage. Many lack generality, as they subscribe to a particular scheduling domain. Others simply implement a particular problem-solving technique, which may be applicable only to a subset of the space of scheduling problems. In addition, most of these libraries fail to provide the required degree of depth and precision. In our approach, we subscribe to the Task-Method-Domain-Application knowledge modeling framework which provides a structured organization for the different components of the library. At the task level, we construct a generic scheduling task ontology to formalize the space of scheduling problems. At the method level, we construct a generic problem-solving model of scheduling that generalizes from the variety of approaches to scheduling problem-solving, which can be found in the literature. The generic nature of this model is demonstrated by constructing seven methods for scheduling as an alternative specialization of the model. Finally, we validated our library on a number of applications to demonstrate its generic nature and effective support for developing scheduling applications. [ABSTRACT FROM AUTHOR]

The construction space scheduling problem has received relatively little attention from researchers and practitioners. We now have sophisticated methods of planning and analyzing the sequence of tasks within the work breakdown structure through time, but the problem of planning where on site those tasks are to be executed is not well-supported especially as those spaces are dynamic as the project progresses. We know that congestion on site reduces output and generates hazards, yet construction planners presently have to rely upon experience and intuition. The research reported here presents a decision support tool for construction project planners to help them address the space scheduling problem. After a review of recent developments in construction space scheduling, the concept of critical space analysis is presented. This forms the basis of decision support tools presented for marking up available space, allocating tasks to spaces, and analyzing and optimizing space loading in relation to the critical path—what we call space-time broking. Requirements capture and evaluation reports from construction planners suggest that the tools presented here have immediate practical relevance. The paper will, therefore, be of interest to both practitioners and researchers. [ABSTRACT FROM AUTHOR]

In Part I of this paper, we presented a large-scale airspace-planning and collaborative decision-making (APCDM) model that is part of a Federal Aviation Administration (FAA)-sponsored effort to enhance the management of the National Airspace System (NAS). Given a set of flights that must be scheduled during some planning horizon, along with alternative surrogate trajectories for each flight, we developed a mixed-integer programming model to select a set of flight plans from among these alternatives, subject to flight safety, airtraffic control workload, and airline equity considerations. The present paper offers insights related to, and a detailed description of, implementing this APCDM model, including the development of a comprehensive cost model, a study for prescribing a set of appropriate parameter values for the overall model, and an investigation on incorporating a suitable set of valid inequalities in the model formulation. Computational results are presented based on several test cases derived from the Enhanced Traffic Management System (ETMS) data provided by the FAA. The results indicate that under plausible probabilistic trajectory error assumptions and with the incorporation of star subgraph convex hull-based valid inequalities, the model offers a viable tool that can be used by the FAA for both tactical and strategic applications. [ABSTRACT FROM AUTHOR]

Online advertising continues to be a significant source of income for many Internet-based organizations. Recent indications of improved economic growth are having an impact on advertisement revenue, with the estimated online advertising revenue in the United States for the fourth quarter of 2003 totaling a record of $2.2 billion. A substantial portion of this income comes from banner advertisements, and efficient scheduling of these advertisements could result in a considerable increase in profits. The problem of scheduling banner advertisements has been observed to be intractable via traditional optimization techniques and has received only limited attention in the literature. In addition, all past attempts to address this problem have been based on an ‘all-or-nothing’ framework, where a customer specifies the exact number of copies of the ad to be displayed over the planning horizon, if it is selected for display by the provider of the advertisement space. This paper extends it to a more realistic setting, where the customer is allowed to specify a set of acceptable display frequencies. The Lagrangian decomposition-based solution approaches presented in this paper are observed to provide good schedules in a reasonable period of time. [ABSTRACT FROM AUTHOR]

The U.S. service sector loses 2.3% of all scheduled labor hours to unplanned absences, but in some industries, the total cost of unplanned absences approaches 20% of payroll expense. The principal reasons for unscheduled absences (personal illness and family issues) are unlikely to abate anytime soon. Despite this, most labor scheduling systems continue to assume perfect attendance. This oversight masks an important but rarely addressed issue in services management: how to recover from short-notice, short-term reductions in planned capacity. In this article, we model optimal responses to unplanned employee absences in multi-server queueing systems that provide discrete, pay-per-use services for impatient customers. Our goal is to assess the performance of alternate absence recovery strategies under various staffing and scheduling regimes. We accomplish this by first developing optimal labor schedules for hypothetical service environments with unreliable workers. We then simulate unplanned employee absences, apply an absence recovery model, and compute system profits. Our absence recovery model utilizes recovery strategies such as holdover overtime, call-ins, and temporary workers. We find that holdover overtime is an effective absence recovery strategy provided sufficient reserve capacity (maximum allowable work hours minus scheduled hours) exists. Otherwise, less precise and more costly absence recovery methods such as call-ins and temporary help service workers may be needed. We also find that choices for initial staffing and scheduling policies, such as planned overtime and absence anticipation, significantly influence the likelihood of successful absence recovery. To predict the effectiveness of absence recovery policies under alternate staffing/scheduling strategies and operating environments, we propose an index based on initial capacity reserves. [ABSTRACT FROM AUTHOR]

Abstract: While an important aspect of airline service quality is on-time arrival performance, increasing on-time reliability while maximizing revenue and minimizing cost is a difficult challenge. This study uses publicly available data to critique the efforts of the top five US airlines to manage domestic on-time performance after the tragic events of September 11, 2001. The central question posed in this paper is whether the substantial improvement in airline on-time arrival performance after these events was due to identifiable improvement in airline scheduling and operations or to a large decline in scheduled flights. [Copyright &y& Elsevier]

Contractors are required by the Michigan Department of Transportation (MDOT) to submit a progress schedule identifying the controlling path of activities for a construction project. During the 2000 construction season, MDOT allowed contractors to submit a progress schedule with overlapping or concurrent controlling operations. Prior to this, only one activity at a time could be controlling on the progress schedule. This paper reports on the results of a research project where the focus was to examine the accuracy of the progress schedules, which only list controlling items. Eight construction projects were studied and a determination of progress schedule accuracy was made. This was done to determine if there was an increase in accuracy of the schedules when concurrent controlling operations were used. Included in the eight projects were four without concurrent controlling activities and four with concurrent controlling activities. A comparison based upon similar projects with and without concurrent activities was made. Additionally, 22 projects were analyzed, all without concurrent controlling activities, to determine the accuracy of progress schedules for two types of projects. The comparison revealed that, in three of the four cases, the accuracy of progress schedules increased with the allowance of concurrent controlling activities. The 22 projects revealed that the accuracy of progress schedules varied considerably. It was also determined that contractors overestimated the duration of activities included in progress schedules. [ABSTRACT FROM AUTHOR]

This paper, motivated by the experiences of a major U.S.-based broadcast television network, presents algorithms and heuristics to schedule commercial videotapes. Major advertisers purchase several slots to air commercials during a given time period on a broadcast network. We study the problem of scheduling advertiser's commercials in the slots it purchased when the same commercial is to be aired multiple times. Under such a situation, the advertisers typically want the airings of a commercial to be as evenly spaced as possible. Thus, our objective is to schedule a set of commercials in a set of available slots such that multiple airings of the same commercial are as evenly spaced as possible. A natural formulation of this problem is a mixed-integer program that can be solved using third-party solvers. We also develop a branch-and-bound algorithm based on a problem-specific bounding scheme. Both approaches fail to solve larger problem instances within a reasonable time frame. We present an alternative mixed-integer program that lends itself to an efficient solution. For solving even larger problems, we present multiple heuristics. [ABSTRACT FROM AUTHOR]