A fuzzy mathematical model for hybrid inventory and purchase optimization in a reverse logistics system considering shortage and warehouse capacity.

Making decisions about the design and implementation of a logistics network is crucial as it has long-term impacts. However, it is important to consider that demand factors and the number of returned items by customers may change over time. Therefore, it is necessary to design a logistics network that can adapt to various demand fluctuations. The main goal of this study is to calculate the quantity of products that should be sent at different times in a supply chain network to minimize the overall cost of reverse logistics and tardiness time. Accordingly, a multi-objective mathematical model is proposed that aims to optimize the total cost and the amount of delay in sending customer orders in a three-level logistics network, assuming that some parameters are uncertain. Additionally, the minimization of waiting time, considering the level of delay in sending, is applied as the second objective function. To handle the uncertainty in the reverse logistics network, a fuzzy approach is implemented, and the proposed model is solved using GAMS software. Furthermore, to solve the mathematical model in large dimensions, the Cuckoo Optimization Algorithm (COA) is applied in MATLAB software, and the results are compared to the global optimal solution. The outcomes show that the proposed algorithm has a desirable performance, as the total values sent to the manufacturer are equal to those obtained from the exact solution, and the objective function value decreases as the number of repetitions increases.

Development and Validation of Lost Days of Labor Productivity Scale to Evaluate the Business Cost of Intimate Partner Violence.

Developing scientific evidence showing the impact of intimate partner violence (IPV) on companies' productivity is an effective way to involve them in IPV prevention. However, there are no suitable and brief self-report instruments available that measure this impact on labor settings. This study develops and assesses the measurement properties of lost days of labor productivity scale based on tardiness, absenteeism, and presenteeism which may be due to IPV. Fourteen items have been developed and tested for 2,017 employees in 306 companies in Ghana, Pakistan, and South Sudan. Descriptive statistics, confirmatory factor analysis, heterotrait-monotrait matrix, and reliability coefficients have been conducted to assess the reliability of the scores. Confirmatory factor analysis indicates a two-factor second-order solution, stable by sex and countries. All subscales demonstrate good reliability, construct and discriminant validity, showing that the scale is a valid and reliable self-report questionnaire, which may measure the impact of IPV on businesses.

Associations of school night sleep duration and circadian preference with middle school-aged student attendance, tardiness, and suspension.

OBJECTIVES: Research has associated both school night sleep duration (SNSD) and circadian preference (CP) with middle school-aged students' attendance and tardiness, but the interaction between these characteristics remains unexplored within this context, along with the impact of SNSD and CP on school suspension likelihood. Thus, this study investigated associations between SNSD, CP, and their interaction with middle school-aged student attendance, tardiness, and suspension, while accounting for sociodemographic characteristics. PARTICIPANTS: About 4175 students from 12 middle schools in the Madison, Wisconsin, Metropolitan School District. METHODS: Students completed a computer-based, sleep-related survey during class. Students reporting SNSD between 4 and 12 hours were included in the final analytical sample (N = 3860; mean age ± standard deviation = 12.0 ± 0.86 years; range = 10-16 years). CP was characterized using the single-item self-morningness/eveningness question. Linear mixed-effects regression estimated associations of SNSD and CP with tardiness and attendance. Logistic mixed-effects regression assessed associations with school suspension. Fully adjusted multilevel models included sociodemographic covariates, nesting students within schools. RESULTS: About 3860 student responses comprised the final sample, which had a SNSD of 8.15 ± 1.37 hours and general eveningness preference. Short-and-long SNSD associated with lower attendance and increased out-of-school suspension. Greater eveningness preference was negatively associated with attendance and tardiness. No SNSD and CP interactions emerged. Associations between sociodemographic characteristics and attendance, tardiness, and suspension were observed. CONCLUSIONS: Results support need for efforts to improve middle school-aged student sleep health and account for eveningness preference. Research clarifying the interactive influence of sleep, circadian, and sociodemographic characteristics on attendance and achievement is warranted.

Intelligent Decision-Making of Scheduling for Dynamic Permutation Flowshop via Deep Reinforcement Learning.

Dynamic scheduling problems have been receiving increasing attention in recent years due to their practical implications. To realize real-time and the intelligent decision-making of dynamic scheduling, we studied dynamic permutation flowshop scheduling problem (PFSP) with new job arrival using deep reinforcement learning (DRL). A system architecture for solving dynamic PFSP using DRL is proposed, and the mathematical model to minimize total tardiness cost is established. Additionally, the intelligent scheduling system based on DRL is modeled, with state features, actions, and reward designed. Moreover, the advantage actor-critic (A2C) algorithm is adapted to train the scheduling agent. The learning curve indicates that the scheduling agent learned to generate better solutions efficiently during training. Extensive experiments are carried out to compare the A2C-based scheduling agent with every single action, other DRL algorithms, and meta-heuristics. The results show the well performance of the A2C-based scheduling agent considering solution quality, CPU times, and generalization. Notably, the trained agent generates a scheduling action only in 2.16 ms on average, which is almost instantaneous and can be used for real-time scheduling. Our work can help to build a self-learning, real-time optimizing, and intelligent decision-making scheduling system.

Impact of sleep problems on daytime function in school life: a cross-sectional study involving Japanese university students.

BACKGROUND: The aims of this study were 1) to clarify the prevalence of sleep problems (insomnia, insufficient sleep, and delayed sleep-wake phase) among Japanese university students; 2) to examine sociodemographic characteristics, lifestyle, and sleep-related symptoms in each sleep problem; and 3) to evaluate the association between the above-mentioned sleep problems and daytime dysfunction in school life. METHODS: Self-report questionnaire surveys were conducted at eight universities in Japan, and we received 1034 valid answers (78% female). The questionnaire consisted of socio-demographic characteristics, information on lifestyle, sleep pattern, sleep-related symptoms, and daytime dysfunction in school life. Groups with insomnia, behaviorally induced insufficient sleep syndrome (BIISS), delayed sleep-wake phase (DSWP), and BIISS + DSWP were defined. To identify the association between sleep problems and daytime dysfunction in school life, the generalized linear mixed effect model was conducted. RESULTS: Sleep duration on weekdays was 5.9 ± 1.2 h, and 38.2% of the students had a sleep duration < 6.0 h. About 16% of the students were categorized as evening-type individuals. More than half of the students (56.1%) had excessive daytime sleepiness. Insomnia was associated with tardiness (aOR: 0.8, 95%CI: 0.7-0.9) and falling asleep during class (aOR: 1.6: 95%CI: 1.4-2.0). BIISS was associated with tardiness (aOR: 1.5, 95%CI: 1.1-2.2) and interference with academic achievement (aOR: 1.9, 95%CI: 1.3-2.6). DSWP and BIISS + DSWP were associated with absence (aOR: 3.4, 95%CI: 2.2-5.1 / aOR: 4.2, 95%CI: 3.2-5.6), tardiness (aOR: 2.7, 95%CI: 1.8-4.1 / aOR: 2.2, 95%CI: 1.6-2.8), falling asleep during class (aOR: 2.6, 95%CI: 1.4-4.8 / aOR: 7.6, 95%CI: 3.3-17.2), and interference with academic achievement (aOR: 2.6, 95%CI: 1.7-3.9 / aOR: 2.1, 95%CI: 1.6-2.8). CONCLUSIONS: Students with DSWP and BIISS + DSWP were significantly associated with daytime dysfunction in school life, i.e. absence, tardiness, falling asleep during class and interference with academic achievement. Students displaying BIISS + DSWP were considered to have a relatively more serious condition compared with those with only insomnia, DSWP, or BIISS. It is therefore of utmost importance that university students aim to prevent DSWP and BIISS which were associated with daytime function in school life.

On Time: A Qualitative Study of Swedish Students', Parents' and Teachers' Views on School Attendance, with a Focus on Tardiness.

Tardiness is a common problem in many schools. It can be understood as an individual risk for future problematic behavior leading to absenteeism, school dropout, exclusion and later health problems. Tardiness can also be examined in relation to a broader social-ecological perspective on health. The aim of this study was to analyze students', school staff's and parents' views on students' tardiness in two Swedish schools. A focus group interview design was used with 21 school personnel, 21 students in grade nine and two parents. The data were analyzed by using thematic content analysis. The results illustrated the main theme-It depends on…-regarding what will happen if a student arrives late to school lessons. This finding is further explained by the subthemes about teachers' signals and reactions and the responses from teachers and students. The conclusion showed the importance of organizing the school day more predictably for the students. Late arrival is a sign of shortcomings in a school organization. It is necessary to develop guidelines related to how to handle students' late arrival based on predictable viewpoints but even more so on how to promote students' sense of belonging and their interest in and motivation for going to school.

Using the Performance Diagnostic Checklist-Human Services to identify an indicated intervention to decrease employee tardiness.

We assessed and reduced the tardiness of 4 direct-care staff employed at a school that provides educational services to children with autism. The Performance Diagnostic Checklist - Human Services was administered to participants and their supervisors to identify one or more indicated interventions. Relative to baseline, tardiness was lower during intervention. The most effective intervention included task clarification, a problem-solving discussion, tokens exchangeable for back-up reinforcers, and weekly graphic feedback. Moreover, participants reported that the intervention components, particularly praise and a token, had high acceptability.

Longitudinal Outcomes of Start Time Delay on Sleep, Behavior, and Achievement in High School.

STUDY OBJECTIVES: To establish whether sleep, health, mood, behavior, and academics improved after a 45-minute delay in high school start time, and whether changes persisted longitudinally. METHODS: We collected data from school records and student self-report across a number of domains at baseline (May 2012) and at two follow-up time points (November 2012 and May 2013), at a public high school in upstate New York. Students enrolled during academic years (AY) 2011-2012 and 2012-2013 completed the Pittsburgh Sleep Quality Index; the DASS-21; the "Owl-Lark" Scale; the Daytime Sleepiness Index; and a brief self-report of health. Reports from school records regarding attendance, tardiness, disciplinary violations, and academic performance were collected for AY 2010-2011 through 2013-2014. RESULTS: Students delayed but did not extend their sleep period; we found lasting improvements in tardiness and disciplinary violations after the start-time delay, but no changes to other variables. At the first follow-up, students reported 20 minutes longer sleep, driven by later rise times and stable bed times. At the second follow-up, students maintained later rise times but delayed bedtimes, returning total sleep to baseline levels. A delay in rise time, paralleling the delay in the start time that occurred, resulted in less tardiness and decreased disciplinary incidents, but larger improvements to sleep patterns may be necessary to affect health, attendance, sleepiness, and academic performance. CONCLUSIONS: Later start times improved tardiness and disciplinary issues at this school district. A delay in start time may be a necessary but not sufficient means to increase sleep time and may depend on preexisting individual differences. COMMENTARY: A commentary on this article appears in this issue on page 267.

Successful interventions to reduce first-case tardiness in Dutch university medical centers: results of a nationwide operating room benchmark study.

BACKGROUND: First-case tardiness is still a common source of frustration. In this study, a nationwide operating room (OR) Benchmark database was used to assess the effectiveness of interventions implemented to reduce tardiness and calculate its economic impact. METHODS: Data from 8 University Medical Centers over 7 years were included: 190,295 elective inpatient first cases. Data were analyzed with SPSS statistics and multidisciplinary focus-group study meetings. Analysis of variance with contrast analysis measured the influence of interventions. RESULTS: Seven thousand ninety-four hours were lost annually to first-case tardiness, which has a considerable economic impact. Four University Medical Centers implemented interventions and effectuated a significant reduction in tardiness, eg providing feedbacks directly when ORs started too late, new agreements between OR and intensive care unit departments concerning "intensive care unit bed release" policy, and a shift in responsibilities regarding transport of patients to the OR. CONCLUSIONS: Nationwide benchmarking can be applied to identify and measure the effectiveness of interventions to reduce first-case tardiness in a university hospital OR environment. The implemented interventions in 4 centers were successful in significantly reducing first-case tardiness.

Periodical capacity setting methods for make-to-order multi-machine production systems.

The paper presents different periodical capacity setting methods for make-to-order, multi-machine production systems with stochastic customer required lead times and stochastic processing times to improve service level and tardiness. These methods are developed as decision support when capacity flexibility exists, such as, a certain range of possible working hours a week for example. The methods differ in the amount of information used whereby all are based on the cumulated capacity demand at each machine. In a simulation study the methods' impact on service level and tardiness is compared to a constant provided capacity for a single and a multi-machine setting. It is shown that the tested capacity setting methods can lead to an increase in service level and a decrease in average tardiness in comparison to a constant provided capacity. The methods using information on processing time and customer required lead time distribution perform best. The results found in this paper can help practitioners to make efficient use of their flexible capacity.