A comprehensive review and evaluation of permutation flowshop heuristics to minimize flowtime

[EN] In recent years, a large number of heuristics have been proposed for the minimization of the total or mean flowtime/completion time of the well-known permutation flowshop scheduling problem. Although some literature reviews and comparisons have been made, they do not include the latest available heuristics and results are hard to compare as no common benchmarks and computing platforms have been employed. Furthermore, existing partial comparisons lack the application of powerful statistical tools. The result is that it is not clear which heuristics, especially among the recent ones, are the best. This paper presents a comprehensive review and computational evaluation as well as a statistical assessment of 22 existing heuristics. From the knowledge obtained after such a detailed comparison, five new heuristics are presented. Careful designs of experiments and analyses of variance (ANOVA) techniques are applied to guarantee sound conclusions. The comparison results identify the best existing methods and show that the five newly presented heuristics are competitive or better than the best performing ones in the literature for the permutation flowshop problem with the total completion time criterionThis research is partially supported by National Science Foundation of China (60874075, 61174187), and Science Foundation of Shandong Province, China (BS2010DX005), and Postdoctoral Science Foundation of China (20100480897). Ruben Ruiz is partially funded by the Spanish Ministry of Science and Innovation, under the project "SMPA-Advanced Parallel Multiobjective Sequencing: Practical and Theorerical Advances" with reference DPI2008-03511/DPI and by the Small and Medium Industry of the Generalitat Valenciana (IMPIVA) and by the European Union through the European Regional Development Fund (FEDER) inside the R+D program "Ayudas dirigidas a Institutos Tecnologicos de la Red IMPIVA" during the year 2011, with project number IMDEEA/2011/142.Pan, Q.; Ruiz García, R. (2013). A comprehensive review and evaluation of permutation flowshop heuristics to minimize flowtime. Computers and Operations Research. 40(1):117-128. https://doi.org/10.1016/j.cor.2012.05.018S11712840

Iterated Greedy methods for the distributed permutation flowshop scheduling problem

[EN] Large manufacturing firms operate more than one production center. As a result, in relation to scheduling problems, which factory manufactures which product is an important consideration. In this paper we study an extension of the well known permutation flowshop scheduling problem in which there is a set of identical factories, each one with a flowshop structure. The objective is to minimize the maximum completion time or makespan among all factories. The resulting problem is known as the distributed permutation flowshop and has attracted considerable interest over the last few years. Contrary to the recent trend in the scheduling literature, where complex nature-inspired or metaphor-based methods are often proposed, we present simple Iterated Greedy algorithms that have performed well in related problems. Improved initialization, construction and destruction procedures, along with a local search with a strong intensification are proposed. The result is a very effective algorithm with little problem-specific knowledge that is shown to provide demonstrably better solutions in a comprehensive and thorough computational and statistical campaign.Ruben Ruiz is partially supported by the Spanish Ministry of Economy and Competitiveness, under the project "SCHEYARD - Optimization of Scheduling Problems in Container Yards" (No. DPI2015-65895-R) financed by FEDER funds. Quan-Ke Pan is supported by the National Natural Science Foundation of China (Grant No. 51575212).Ruiz García, R.; Pan, Q.; Naderi, B. (2019). Iterated Greedy methods for the distributed permutation flowshop scheduling problem. Omega. 83:213-222. https://doi.org/10.1016/j.omega.2018.03.004S2132228

Iterated search methods for earliness and tardiness minimization in hybrid flowshops with due windows

[EN] In practice due dates usually behave more like intervals rather than specific points in time. This paper studies hybrid flowshops where jobs, if completed inside a due window, are considered on time. The objective is therefore the minimization of the weighted earliness and tardiness from the due window. This objective has seldom been studied and there are almost no previous works for hybrid flowshops. We present methods based on the simple concepts of iterated greedy and iterated local search. We introduce some novel operators and characteristics, like an optimal idle time insertion procedure and a two stage local search where, in the second stage, a limited local search on a exact representation is carried out. We also present a comprehensive computational campaign, including the reimplementation and comparison of 9 competing procedures. A thorough evaluation of all methods with more than 3000 instances shows that our presented approaches yield superior results which are also demonstrated to be statistically significant. Experiments also show the contribution of the new operators in the presented methods. (C) 2016 Elsevier Ltd. All rights reserved.The authors would like to thank Professors Lofti Hidri and Mohamed Haouari for sharing with us the source codes and explanations of the lower bounds. Quan-Ke Pan is supported by the National Natural Science Foundation of China (Grant No. 51575212), Program for New Century Excellent Talents in University (Grant No. NCET-13-0106), Science Foundation of Hubei Province in China (Grant No. 2015CFB560), Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 20130042110035), Key Laboratory Basic Research Foundation of Education Department of Liaoning Province (LZ2014014), Open Research Fund Program of the State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, China. Ruben Ruiz and Pedro Alfaro-Fernandez are supported by the Spanish Ministry of Economy and Competitiveness, under the project "SCHEYARD Optimization of Scheduling Problems in Container Yards" (No. DPI2015-65895-R) financed by FEDER funds.Pan, Q.; Ruiz García, R.; Alfaro-Fernandez, P. (2017). Iterated search methods for earliness and tardiness minimization in hybrid flowshops with due windows. Computers & Operations Research. 80:50-60. https://doi.org/10.1016/j.cor.2016.11.022S50608

ZnCdS Dotted with Highly Dispersed Pt Supported on SiO2 Nanospheres Promoting Photocatalytic Hydrogen Evolution

[EN] The efficiency of solar hydrogen evolution closely depends on the fast transfer of charge carriers and the effective use of visible light. In this work, a novel photocatalyst SiO2/ZnCdS/Pt was successfully prepared to solve these two problems. An artistic structure of the photocatalyst was constructed and ZnCdS was successfully wrapped on the surface of SiO2 spheres with uniform Pt nanoparticles (NPs) in a size of 4.1 +/- 0.7 nm highly dispersed on the ZnCdS shell through the self-assembly method. Pt NPs can absorb the scattered light in the near field of SiO2 spheres. With the synergistic effect of SiO2 spheres and small highly dispersed Pt NPs, the absorption of visible light was significantly promoted. Meanwhile, the electron-hole recombination was also effectively inhibited, thus improving the photocatalytic activity. The hydrogen production activity of the highly efficient photocatalyst was as high as 8.3 mmol g(-1) h(-1) under visible light (lambda > 420 nm). The photocatalytic activity of SiO2/ZnCdS/Pt was 2.9 times higher than that of the ZnCdS/Pt photocatalyst.This work was supported by the National Natural Science Foundation of China (21976111), Shandong Provincial Natural Science Foundation (ZR2019MB052), and Large Instrument Open Foundation of Shandong Normal University (KFJJ2019004; KFJJ2021006).Liu, K.; Peng, L.; Zhen, P.; Chen, L.; Song, S.; García Gómez, H.; Sun, C. (2021). ZnCdS Dotted with Highly Dispersed Pt Supported on SiO2 Nanospheres Promoting Photocatalytic Hydrogen Evolution. The Journal of Physical Chemistry C. 125(27):14656-14665. https://doi.org/10.1021/acs.jpcc.1c0353514656146651252

Broadband radio communications in subway stations and tunnels

Broadband radio communication systems are very important for railway traffic control systems and passengers network services. Nowadays, even though 4G LTE (Long Term Evolution) has deployed for commercial use with excellent results in open areas, it is still lack of knowledge regarding to how such broadband signals propagate inside complex environments with many complex structures that affect propagation such as subway tunnels and stations. For this reason, the aim of the presented measurements in this paper is to model the response of the broadband channel at 1000 MHz and 2450 MHz in the subway environments. These measurements focus on three types of scenarios: subway stations, straight tunnels and a train effect the signal. The results provide detailed information about the propagation channel, which can be useful to develop a broadband propagation model for underground communication systems

Learning from Prior Designs for Facility Layout Optimization

Peer reviewe

Molecular transport calculations with Wannier functions

We present a scheme for calculating coherent electron transport in atomic-scale contacts. The method combines a formally exact Green's function formalism with a mean-field description of the electronic structure based on the Kohn-Sham scheme of density functional theory. We use an accurate plane-wave electronic structure method to calculate the eigenstates which are subsequently transformed into a set of localized Wannier functions (WFs). The WFs provide a highly efficient basis set which at the same time is well suited for analysis due to the chemical information contained in the WFs. The method is applied to a hydrogen molecule in an infinite Pt wire and a benzene-dithiol (BDT) molecule between Au(111) surfaces. We show that the transmission function of BDT in a wide energy window around the Fermi level can be completely accounted for by only two molecular orbitals.Comment: 15 pages, 12 figures, submitted to Chemical Physic

Correlational analysis and predictive validity of psychological constructs related with pain in fibromyalgia

<p>Abstract</p> <p>Background</p> <p>Fibromyalgia (FM) is a prevalent and disabling disorder characterized by a history of widespread pain for at least three months. Pain is considered a complex experience in which affective and cognitive aspects are crucial for prognosis. The aim of this study is to assess the importance of pain-related psychological constructs on function and pain in patients with FM.</p> <p>Methods</p> <p>Design</p> <p>Multicentric, naturalistic, one-year follow-up study.</p> <p><it>Setting and study sample</it>. Patients will be recruited from primary care health centres in the region of Aragon, Spain. Patients considered for inclusion are those aged 18-65 years, able to understand Spanish, who fulfil criteria for primary FM according to the American College of Rheumatology, with no previous psychological treatment.</p> <p>Measurements</p> <p>The variables measured will be the following: main variables (pain assessed with a visual analogue scale and with sphygmomanometer and general function assessed with Fibromyalgia Impact Questionnaire, and), psychological constructs (pain catastrophizing, pain acceptance, mental defeat, psychological inflexibility, perceived injustice, mindfulness, and positive and negative affect), and secondary variables (sociodemographic variables, anxiety and depression assessed with Hospital Anxiety and Depression Scale, and psychiatric interview assessed with MINI). Assessments will be carried at baseline and at one-year follow-up.</p> <p>Main outcome</p> <p>Pain Visual Analogue Scale.</p> <p>Analysis</p> <p>The existence of differences in socio-demographic, main outcome and other variables regarding pain-related psychological constructs will be analysed using Chi Square test for qualitative variables, or Student <it>t </it>test or variance analysis, respectively, for variables fulfilling the normality hypothesis. To assess the predictive value of pain-related psychological construct on main outcome variables at one-year follow-up, use will be made of a logistic regression analysis adjusted for socio-demographic and clinical variables. A Spearman Rho non-parametric correlation matrix will be developed to determine possible overlapping between pain-related psychological constructs.</p> <p>Discussion</p> <p>In recent years, the relevance of cognitive and affective aspects for the treatment of chronic pain, not only in FM but also in other chronic pain diseases, has been widely acknowledged. However, the relative importance of these psychological constructs, the relationship and possible overlapping between them, or the exact meaning of them in pain are not enough known.</p

Undergraduate students as co-producers in the creation of first-year practical class resources

Undergraduate students are increasingly working with academic staff to evaluate and design teaching materials in Higher Education, thereby moving from being passive consumers of knowledge to genuine partners in their education. Here we describe a student partnership project run at the University of Cambridge, which aimed to improve undergraduate biology practical class teaching. Student interns were recruited to act as researchers, pedagogical consultants and producers of teaching resources. Research by the interns revealed that students with limited practical experience at high-school level tended to have lower confidence and more negative responses to first-year university practical classes than peers with more experience. Interns and academics therefore redesigned the workflow for practicals to include online pre- and post-practical tutorials to support understanding and consolidation of laboratory-based material, which included student-produced quizzes and videos. We reflect on the process of building the partnership, and explore the value of partnership approaches in Higher Education.This work was supported by the University of Cambridge Teaching and Learning Innovation Fund [AHAV]