An efficient heuristic for the multi-vehicle one-to-one pickup and delivery problem with split loads

In this study, we consider the Multi-vehicle One-to-one Pickup and Delivery Problem with Split Loads (MPDPSL). This problem is a generalization of the one-to-one Pickup and Delivery Problem (PDP) where each load can be served by multiple vehicles as well as multiple stops by the same vehicle. In practice, split deliveries is a viable option in many settings where the load can be physically split, such as courier services of third party logistics operators. We propose an efficient heuristic that combines the strengths of Tabu Search and Simulated Annealing for the solution of MPDPSL. Results from experiments on two problems sets in the literature indicate that the heuristic is capable of producing good quality solutions in reasonable time. The experiments also demonstrate that up to 33\% savings can be obtained by allowing split loads; however, the magnitude of savings is dependent largely on the spatial distribution of the pickup and delivery points

Importance of ectopic thyroid tissue detected in the midline of the neck: single center experience

ABSTRACT Objective: Ectopic thyroid tissue (ETT) is a rare abnormality of the thyroid gland and the true prevalence and importance is not known. The aim of this study was to evaluate ultrasonography (US) guided fine needle aspiration biposy (FNAB) results, sonographic features, and frequency of ETT detected in the midline of the neck. Subjects and methods: Five thousand five hundred and twenty outpatients who were referred to our thyroid clinic between September 2010 and April 2012 and underwent thyroid US, were retrospectively analyzed. Patients with ETT, detected in the midline of the neck in US were included in the study. Thyroid functions, sonographic features, and US guided FNAB results were evaluated. Results: There were 81 (81.8%) female and 18 (18.2%) male patients with a mean age of 50.9 ± 11.7. The ETT in the midline was present in 1.79% (99/5,520) of the patients. In the majority of the patients, benign sonographic features (isoechoic, regular margin, type 1 vascularization) were detected. There were 92 (92.9%) patients with a previous history of thyroidectomy and all were histopathologically benign. In 7 (7.1%) patients, there was no history of thyroid operation. FNAB results of ETT were benign. Conclusion: This study evaluated the importance of ETT detected incidentally in the midline of the neck. Especially in patients with a history of thyroidectomy, the thyroid masses in the midline of the neck can be found as incidental with imaging methods. Our results suggests that the incidence of malignancy in this group is much lower than orthotopic thyroid nodules and they are often benign. Arch Endocrinol Metab. 2016;60(3):231-

Transit coordination with heterogeneous headways

We consider the transit coordination problem with heterogeneous headways. Timetables with heterogeneous headways improve coordination between transit lines and reduce transfer time for connecting passengers. Unfortunately, deviating from homogeneous headways impacts adversely on initial waiting times experienced prior to embarking on the initial vehicle of a trip. We focus on this trade-off between transfer waiting time and initial waiting time, which has not been explored previously, and develop a mathematical model to quantify the benefits of heterogeneous headways. We also propose a genetic algorithm (GA) to solve the transit coordination problem with heterogeneous headways and demonstrate the benefit of heterogeneous headways based on two examples from the literature and one real-life example based on the rail transit network of Istanbul. Computational results suggest that the GA solves the transit coordination problem within a reasonable time and significant benefits can be achieved by adopting timetables with heterogeneous headways

Pre-service Teachers’ Reflective Judgment Skills in the Context of Socio-scientific Issues based Inquiry Laboratory Course

There are certain threats embedded in scientific development that confront society. Gaining practical and instrumental experiences in addressing topics related to the major challenges that confront society today can be possible by tapping the socio-scientific issues as a part of science teaching and learning. This research aimed to explore pre-service teachers’ reflective judgment skills in socio-scientific issues based inquiry science laboratory course. The participants of the research were 20 pre-service teachers at a research oriented public university. Qualitative case study research design was used in this study. The laboratory manuals and semi-structured interviews were used as data collection tools. Data were analyzed by using King and Kitchener’s (1994) reflective judgment framework. Results of the study showed that pre-service teachers’ reflective judgment scores tended to increase from the first experiment to the last experiment. Results suggested that exploring reflective judgment in socio-scientific contexts is beneficial for allowing pre-service teachers to actively engage in knowledge construction

Dynamic programming and mixed integer programming based algorithms for the online glass cutting problem with defects and production targets

<p>In flat glass manufacturing, glass products of various dimensions are cut from a glass ribbon that runs continuously on a conveyor belt. Placement of glass products on the glass ribbon is restricted by the defects of varying severity located on the ribbon as well as the quality grades of the products to be cut. In addition to cutting products, a common practice is to remove defective parts of the glass ribbon as scrap glass. As the glass ribbon moves continuously, cutting decisions need to be made within seconds, which makes this online problem very challenging. A simplifying assumption is to limit scrap cuts to those made immediately behind a defect (a cut-behind-fault or CBF). We propose an online algorithm for the glass cutting problem that solves a series of static cutting problems over a rolling horizon. We solve the static problem using two methods: a dynamic programming algorithm (DP) that utilises the CBF assumption and a mixed integer programming (MIP) formulation with no CBF restriction. While both methods improve the process yield substantially, the results indicate that MIP significantly outperforms DP, which suggests that the computational benefit of the CBF assumption comes at a cost of inferior solution quality.</p

Pre-service Teachers’ Reflective Judgment Skills in the Context of Socio-scientific Issues based Inquiry Laboratory Course

There are certain threats embedded in scientific development that confront society. Gaining practical and instrumental experiences in addressing topics related to the major challenges that confront society today can be possible by tapping the socio-scientific issues as a part of science teaching and learning. This research aimed to explore pre-service teachers’ reflective judgment skills in socio-scientific issues based inquiry science laboratory course. The participants of the research were 20 pre-service teachers at a research oriented public university. Qualitative case study research design was used in this study. The laboratory manuals and semi-structured interviews were used as data collection tools. Data were analyzed by using King and Kitchener’s (1994) reflective judgment framework. Results of the study showed that pre-service teachers’ reflective judgment scores tended to increase from the first experiment to the last experiment. Results suggested that exploring reflective judgment in socio-scientific contexts is beneficial for allowing pre-service teachers to actively engage in knowledge construction

A branch and cut algorithm for the multi-vehicle one-to-one pickup and delivery problem with split loads

In this work we deal with the Multi-vehicle One-to-one Pickup and Delivery Problem with Split Loads (MPDPSL). This problem is a generalization of the one-to-one Pickup and Delivery Problem (PDP) where each load can be served by multiple stops by the same vehicle. In practice split deliveries is a viable option in many settings such as courier services of third party logistics operators. We propose a branch-and-cut algorithm which employs valid inequalities devised for special cases of the MPDPSL, such as the Dial-a-Ride Problem, PDP and Split Delivery Vehicle Routing Problem. According to our computational experiments with randomly generated test instances, we may claim that the proposed algorithm can be used for small sized instances

Importance of ectopic thyroid tissue detected in the midline of the neck: single center experience

Objective Ectopic thyroid tissue (ETT) is a rare abnormality of the thyroid gland and the true prevalence and importance is not known. The aim of this study was to evaluate ultrasonography (US) guided fine needle aspiration biposy (FNAB) results, sonographic features, and frequency of ETT detected in the midline of the neck. Subjects and methods Five thousand five hundred and twenty outpatients who were referred to our thyroid clinic between September 2010 and April 2012 and underwent thyroid US, were retrospectively analyzed. Patients with ETT, detected in the midline of the neck in US were included in the study. Thyroid functions, sonographic features, and US guided FNAB results were evaluated. Results There were 81 (81.8%) female and 18 (18.2%) male patients with a mean age of 50.9 ± 11.7. The ETT in the midline was present in 1.79% (99/5,520) of the patients. In the majority of the patients, benign sonographic features (isoechoic, regular margin, type 1 vascularization) were detected. There were 92 (92.9%) patients with a previous history of thyroidectomy and all were histopathologically benign. In 7 (7.1%) patients, there was no history of thyroid operation. FNAB results of ETT were benign. Conclusion This study evaluated the importance of ETT detected incidentally in the midline of the neck. Especially in patients with a history of thyroidectomy, the thyroid masses in the midline of the neck can be found as incidental with imaging methods. Our results suggests that the incidence of malignancy in this group is much lower than orthotopic thyroid nodules and they are often benign