Integrated capacitated lot sizing and scheduling problems in a flexible flow line

The lot sizing and scheduling problem in a Flexible Flow Line (FFL) has extensive real-world applications in many industries. An FFL consists of several production stages in series with parallel machines at each stage. The decisions to be taken are the determination of production quantities (lots), machine assignments and production sequences (schedules) on each machine at each stage in an FFL. Lot sizing and scheduling problems are closely interrelated. Solving them separately and then coordinating their interdependencies is often ineffective. However due to their complexity, there is a lack of mathematical modelling and solution procedures in the literature to combine and jointly solve them.Up to now most research has been focused on combining lotsizing and scheduling for the single machine configuration, and research on other configurations like FFL is sparse. This thesis presents several mathematical models with practical assumptions and appropriate algorithms, along with experimental test problems, for simultaneously lotsizing and scheduling in FFL. This problem, called the ‘General Lot sizing and Scheduling Problem in a Flexible Flow Line’ (GLSP-FFL). The objective is to satisfy varying demand over a finite planning horizon with minimal inventory, backorder and production setup costs. The problem is complex as any product can be processed on any machine, but these have different processing rates and sequence-dependent setup times & costs. As a result, even finding a feasible solution of large problems in reasonable time is impossible. Therefore the heuristic solution procedure named Adaptive Simulated Annealing (ASA), with four well-designed initial solutions, is designed to solve GLSP-FFL.A further original contribution of this study is to design linear mixed-integer programming (MILP) formulations for this problem, incorporating all necessary features of setup carryovers, setup overlapping, non-triangular setup while allowing multiple lot production per periods, lot splitting and sequencing through ATSP-adaption based on a variety of subtour elimination

Evaluation of the relationship between serum estradiol levels on human chorionic gonadotropin administration day and intracytoplasmic sperm injection outcomes: A retrospective population-based study

Background: The correlation between high estradiol (E2) levels induced by controlled ovarian hyperstimulation (COH) and pregnancy is controversial. Objective: To assess the effect of serum E2 levels on the day of human chorionic gonadotropin administration on the intracytoplasmic sperm injection (ICSI) outcome. Materials and Methods: The current study included 551 participants who had undergone ICSI between May 2014 and May 2016. Based on E2 levels, the individuals aged < 37 yr (n = 502) and 37-42 yr (n = 49) were categorized into six and three groups, respectively. ICSI outcomes including the number of retrieved oocytes (NRO), number of embryos (NE), pregnancy rate, and abortion rate were analyzed in both groups. Results: Among participants aged < 37 yr, the NRO and NE were 8.69 ± 3.82 and 5.24 ± 2.32, respectively and they had a significant correlation with the E2 level on human chorionic gonadotropin administration day (p < 0.001 for both). Among participants aged > 37 yr, NRO and NE were 5.18 ± 3.17 and 3.40 ± 2.23, respectively, and the NRO (p < 0.001), NE (p < 0.001), pregnancy rate (p < 0.001), abortion rate (p = 0.007), and the number of grade A and B embryos (p = 0.003) had a significant association with the E2 level. Conclusion: COH is a costly procedure that may have negative effects on endometrial receptivity. Thus, in order to prevent these effects and also to reduce the costs of COH, we recommend gaining optimum number of oocytes rather than maximum number during the procedure. Key words: Intracytoplasmic sperm injection, In vitro fertilization, Estradiol, Pregnancy

Sonographic Cervical Markers at the Second Trimester for the Prediction of Preterm Birth

Background: This study aimed to assess the diagnostic value of novel ultrasonographic markers, Anterior Uterocervical Angle (AUA), Cervical Consistency Index (CCI) and Cervical Glandular Area (CGA) in the Prediction of Preterm Birth (PTB), in a general population. Methods: We conducted a prospective cohort study on singleton gestations between 16 -24 weeks undergoing transvaginal sonography for Cervical Length (CL) screening. AUA, CCI and CGA were evaluated. The primary outcome was prediction of spontaneous PTB before 37 weeks’ gestation by UCA, CCI and CGA. The secondary outcome was evaluating performance of these markers alone and in combination with CL to predict PTB. Results: A total of 310 women were studied. The rate of PTB in this population was 10.6 % for delivery before 37 weeks. In the PTB group, the shorter CL, the wider AUA and the lower CCI were significant, but the CGA width and area were not significantly different in term and PTB groups. The optimal cut-off based on the ROC curve was 33.15 mm for CL (sensitivity: 57%; specificity: 68%), 102.5 degrees for AUA (sensitivity: 50%; specificity: 80%), and 60.3% for CCI (sensitivity: 43%; specificity: 68%). Conclusions: Our data indicate that the combination of CL and CCI (positive likelihood ratio:3; negative likelihood ratio:0.7) and the combination of CL and AUA (positive likelihood ratio:4.8; negative likelihood ratio:0.76) are better methods for the prediction of spontaneous PTB before 37 weeks; and can be used as a screening tool in the second trimester

The Role of Pre-Pregnancy Body Mass Index (BMI) in Predicting Maternal Serum Leptin

Background: The key role of leptin is regulation of appetite and body lipid and pregnancy is a condition associated with overeating, reduction in heating and adaptation of lipid cells, culminating in increased body fat mass. So, this study was conducted to examine the relationship between changes in pre-pregnancy BMI and leptin. Methods: This Longitudinal study was conducted on 45 women in the first trimester of pregnancy using a longitudinal approach and convenience sampling method in Tehran city in 2015. The mothers in terms of pre-pregnancy BMI were divided into two groups: group A (n=22 with normal BMI) and group B (n=23 with high BMI), with maternal serum leptin being taken in 6-12 weeks and 15-20 weeks of pregnancy and measured by enzyme-linked immunosorbent assay (ELISA). The statistical data were analyzed by SPSS V.21 using Kolmogorov Smirnov, independent t-test, two-sample Chi square, Mann-Whitney, Regression, Pearson and Landa tests with P.V<0.05. Results: The mean age of mothers in the present study was 27.47±5.55 years with a minimum age of 19 and a maximum age of 37 years. The mean plasma leptin of the first and second trimesters of pregnancy was significantly higher in the high BMI group than in the normal group. The correlation showed that the first trimester leptin and changes in leptin levels of pregnancy with pre-pregnancy BMI were significantly higher in the normal group (P=0.04 and P=0.003). Conclusions: BMI before and during pregnancy can be a predictor of maternal serum leptin in pregnancy weight gain. &nbsp

The Role of Pre-Pregnancy Body Mass Index (BMI) in Predicting Maternal Serum Leptin

Background: The key role of leptin is regulation of appetite and body lipid and pregnancy is a condition associated with overeating, reduction in heating and adaptation of lipid cells, culminating in increased body fat mass. So, this study was conducted to examine the relationship between changes in pre-pregnancy BMI and leptin. Methods: This Longitudinal study was conducted on 45 women in the first trimester of pregnancy using a longitudinal approach and convenience sampling method in Tehran city in 2015. The mothers in terms of pre-pregnancy BMI were divided into two groups: group A (n=22 with normal BMI) and group B (n=23 with high BMI), with maternal serum leptin being taken in 6-12 weeks and 15-20 weeks of pregnancy and measured by enzyme-linked immunosorbent assay (ELISA). The statistical data were analyzed by SPSS V.21 using Kolmogorov Smirnov, independent t-test, two-sample Chi square, Mann-Whitney, Regression, Pearson and Landa tests with P.V<0.05. Results: The mean age of mothers in the present study was 27.47±5.55 years with a minimum age of 19 and a maximum age of 37 years. The mean plasma leptin of the first and second trimesters of pregnancy was significantly higher in the high BMI group than in the normal group. The correlation showed that the first trimester leptin and changes in leptin levels of pregnancy with pre-pregnancy BMI were significantly higher in the normal group (P=0.04 and P=0.003). Conclusions: BMI before and during pregnancy can be a predictor of maternal serum leptin in pregnancy weight gain. &nbsp

A novel flexible model for lot sizing and scheduling with non-triangular, period overlapping and carryover setups in different machine configurations

© 2017, Springer Science+Business Media New York. This paper develops and tests an efficient mixed integer programming model for capacitated lot sizing and scheduling with non-triangular and sequence-dependent setup times and costs incorporating all necessary features of setup carryover and overlapping on different machine configurations. The model’s formulation is based on the asymmetric travelling salesman problem and allows multiple lots of a product within a period. The model conserves the setup state when no product is being processed over successive periods, allows starting a setup in a period and ending it in the next period, permits ending a setup in a period and starting production in the next period(s), and enforces a minimum lot size over multiple periods. This new comprehensive model thus relaxes all limitations of physical separation between the periods. The model is first developed for a single machine and then extended to other machine configurations, including parallel machines and flexible flow lines. Computational tests demonstrate the flexibility and comprehensiveness of the proposed models

Mapping 123 million neonatal, infant and child deaths between 2000 and 2017

Since 2000, many countries have achieved considerable success in improving child survival, but localized progress remains unclear. To inform efforts towards United Nations Sustainable Development Goal 3.2—to end preventable child deaths by 2030—we need consistently estimated data at the subnational level regarding child mortality rates and trends. Here we quantified, for the period 2000–2017, the subnational variation in mortality rates and number of deaths of neonates, infants and children under 5 years of age within 99 low- and middle-income countries using a geostatistical survival model. We estimated that 32% of children under 5 in these countries lived in districts that had attained rates of 25 or fewer child deaths per 1,000 live births by 2017, and that 58% of child deaths between 2000 and 2017 in these countries could have been averted in the absence of geographical inequality. This study enables the identification of high-mortality clusters, patterns of progress and geographical inequalities to inform appropriate investments and implementations that will help to improve the health of all populations

Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017

A double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4% (62.3 (55.1–70.8) million) to 6.4% (58.3 (47.6–70.7) million), but is predicted to remain above the World Health Organization’s Global Nutrition Target of <5% in over half of LMICs by 2025. Prevalence of overweight increased from 5.2% (30 (22.8–38.5) million) in 2000 to 6.0% (55.5 (44.8–67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic

Production lot sizing and scheduling with non-triangular sequence-dependent setup times

[NB some mathematical symbols in this abstract may not be correctly reproduced - please check the full text.] This article considers a production lot sizing and scheduling problem with sequence dependent setup times that are not triangular. Consider, for example, a product p that contaminates some other product r unless either a decontamination occurs as part of a substantial setup time stpr or there is a third product q that can absorb p’s contamination. When setup times are triangular then stpr ≤ stpq + stqr and there is always an optimal lot sequence with at most one lot (AM1L) per product per period. However, product q’s ability to absorb p’s contamination presents a shortcut opportunity and could result in shorter non-triangular setup times such that stpr > stpq +stqr. This implies that it can sometimes be optimal for a shortcut product such as q to be produced in more than one lot within the same period, breaking the AM1L assumption in much research. This article formulates and explains a new optimal model that not only permits multiple lots (ML) per product per period, but also prohibits subtours using a polynomial number of constraints rather than an exponential number. Computational tests demonstrate the effectiveness of the ML model, even in the presence of just one decontaminating shortcut product, and its fast speed of solution compared to the equivalent AM1L model