Due-Window Assignment and Scheduling with Multiple Rate-Modifying Activities under the Effects of Deterioration and Learning

This paper discusses due-window assignment and scheduling with multiple rate-modifying activities. Multiple types of rate-modifying activities are allowed to perform on a single machine. The learning effect and job deterioration are also integrated concurrently into the problem which makes the problem more realistic. The objective is to find jointly the optimal location to perform multiple rate-modifying activities, the optimal job sequence, and the optimal location and size of the due window to minimize the total earliness, tardiness, and due-window-related costs. We propose polynomial time algorithms for all the cases of the problem under study

Investigation of cracks in GaN films grown by combined hydride and metal organic vapor-phase epitaxial method

Cracks appeared in GaN epitaxial layers which were grown by a novel method combining metal organic vapor-phase epitaxy (MOCVD) and hydride vapor-phase epitaxy (HVPE) in one chamber. The origin of cracks in a 22-μm thick GaN film was fully investigated by high-resolution X-ray diffraction (XRD), micro-Raman spectra, and scanning electron microscopy (SEM). Many cracks under the surface were first observed by SEM after etching for 10 min. By investigating the cross section of the sample with high-resolution micro-Raman spectra, the distribution of the stress along the depth was determined. From the interface of the film/substrate to the top surface of the film, several turnings were found. A large compressive stress existed at the interface. The stress went down as the detecting area was moved up from the interface to the overlayer, and it was maintained at a large value for a long depth area. Then it went down again, and it finally increased near the top surface. The cross-section of the film was observed after cleaving and etching for 2 min. It was found that the crystal quality of the healed part was nearly the same as the uncracked region. This indicated that cracking occurred in the growth, when the tensile stress accumulated and reached the critical value. Moreover, the cracks would heal because of high lateral growth rate

Efficacy and safety of low-dose IL-2 in the treatment of systemic lupus erythematosus: A randomised, double-blind, placebo-controlled trial

Objectives Open-labelled clinical trials suggested that low-dose IL-2 might be effective in treatment of systemic lupus erythematosus (SLE). A double-blind and placebocontrolled trial is required to formally evaluate the safety and efficacy of low-dose IL-2 therapy. Methods A randomised, double-blind and placebocontrolled clinical trial was designed to treat 60 patients with active SLE. These patients received either IL-2 (n=30) or placebo (n=30) with standard treatment for 12 weeks, and were followed up for additional 12 weeks. IL-2 at a dose of 1 million IU or placebo was administered subcutaneously every other day for 2 weeks and followed by a 2-week break as one treatment cycle. The primary endpoint was the SLE Responder Index-4 (SRI-4) at week 12. The secondary endpoints were other clinical responses, safety and dynamics of immune cell subsets. Results At week 12, the SRI-4 response rates were 55.17% and 30.00% for IL-2 and placebo, respectively (p=0.052). At week 24, the SRI-4 response rate of IL-2 group was 65.52%, compared with 36.67% of the placebo group (p=0.027). The primary endpoint was not met at week 12. Low-dose IL-2 treatment resulted in 53.85% (7/13) complete remission in patients with lupus nephritis, compared with 16.67% (2/12) in the placebo group (p=0.036). No serious infection was observed in the IL-2 group, but two in placebo group. Besides expansion of regulatory T cells, low-dose IL-2 may also sustain cellular immunity with enhanced natural killer cells. Conclusions Low-dose IL-2 might be effective and tolerated in treatment of SThe work was supported by the National Natural Science Foundation of China (31530020,31570880,81471601,81601417 and 81701598), Peking-Tsinghua Center for Life Sciences to ZG LI, Beijing Sci-Tech Committee Z171100000417007,Clinical Medicine Plus X-Young Scholars Project of Peking University (PKU2019LCXQ013) supported by the Fundamental Research Funds for the Central Universities, Beijing Nova Program Z171100001117025, National Key Research and Development Program of China (2017YFC0909003 to DY), BellberryViertel Senior Medical Research Fellowship to DY and Beijing SL PHARM

Multitasking Scheduling Problems with Deterioration Effect

Multitasking scheduling problems with a deterioration effect incurred by coexisting behavioral phenomena in human-related scheduling systems including deteriorating task processing times and deteriorating rate-modifying activity (DRMA) of human operators are addressed. Under the assumption of this problem, the processing of a selected task suffers from the joint effect of available but unfinished waiting tasks, the position-dependent deterioration of task processing time, and the DRMA of human operators. Traditionally, these issues have been considered separately; herein, we address their integration. We propose optimal algorithms to solve the problems to minimize makespan and the total absolute differences in completion time, respectively. Based on the analysis, some special cases and extensions are also discussed

Organic vs. Non-Organic Food Products: Credence and Price Competition

International audienceWe analyze the organic and non-organic production choices of two firms by considering customers' trust in organic food products. In the context of customers' possible willingness to pay a premium price and their mistrust in organic food products, two firms first make choices on offering organic and non-organic food products. If offering organic products, a firm can further invest in the credence system to increase customers' trust in their organic products. At the final stage, two firms determine prices. We provide serval insights. First, we characterize the market conditions in which only one firm, both firms or neither firm will choose to offer organic food products. We find that the higher the production costs or credence investment costs for organic food products are, the more likely firms are to choose to produce non-organic food products. Second, if it is expensive enough to invest in organic credence, offering organic food products may still be uncompetitive, even if organic production cost appears to have no disadvantage compared to non-organic food products. Third, we highlight how the prices of organic food products in equilibrium are affected by market parameters. We show that when only one firm offers organic food products, this firm tends to offer a relatively low price if organic credence investment is expensive. Fourth, we highlight how one firm's credence investment decision in equilibrium can be affected by the product type choice of the other firm. We find that the investment in organic credence is lower when both firms offer organic food products compared with the case when only one firm offers organic food products

Multitasking scheduling problems with a rate-modifying activity

International audienc

Problèmes d'ordonnancement avec affectation de ressource consommable et effet d'apprentissage

This thesis addresses scheduling problems with consumable resource allocation and learning effect. In traditional deterministic scheduling problems, job processing times are assumed to be constant. However, this assumption is not always appropriate in many real life production and service operations since practical issues, including limited consumable resources, human characteristics (learning effect), usually affect job processing times, which change the whole scheduling process and lead to new characteristics to decision-making and scheduling results. It is therefore necessary and reasonable to study scheduling problems with these features. Based on the above two issues, this thesis mainly concerns four scheduling problems including group technology, rate-modifying activity (RMA), past-sequence-dependent setup times, and due-windows. It is worth to note that RMA which reflects the situations of ma-chines is also a key factor considered. It is involved in all studied problems except the first one. This thesis is also a work considering comprehensively new characteristics of consumable resources, human, and machines although we just organize this thesis from the viewpoint of consumable resource allocation and learning effect. For each problem, we propose a scheduling model, design an exact algorithm, and analyze the complexityCette thèse s intéresse aux problèmes d ordonnancement à une machine où les durées opératoires des tâches peuvent dépendre de différents paramètres. Dans les problèmes d ordonnancement traditionnels, les durées opératoires sont souvent supposées constantes. Cette hypothèse n est pas toujours valable dans certains problèmes réels d'ordonnancement en production ou en service. La durée opératoire d'une tâche peut en effet varier selon la quantité de ressources consommables allouées, la performance des opérateurs et l état des ressources matérielles utilisées, etc. L ordonnancement optimal peut donc être différent. Nous nous intéressons à quatre problèmes d ordonnancement avec différentes configurations des facteurs suivants : changement de productivité par la maintenance, quantité de ressources consommables utilisées, effet d apprentissage, technologie de groupe, temps de réglage et fenêtres horaires dues. Le changement de productivité par la maintenance, qui reflète l'état des machines, est un facteur clé de cette thèse. Il est présent dans tous les problèmes étudié, sauf pour le premier. Cette thèse considère globalement les nouvelles caractéristiques telles que les ressources consommables, les ressources humaines et les machines bien qu'elle soit organisée sous l'angle des ressources consommables et l'effet d'apprentissage. Pour chaque problème considéré, nous construisons d abord un modèle mathématique. Après l analyse du modèle construit, nous proposons un algorithme exact de résolution. Enfin la complexité de l algorithme est étudiéeTROYES-SCD-UTT (103872102) / SudocSudocFranceChinaFRC

The capacitated plant location problem with customers and suppliers matching

International audienceThis paper introduces a new problem called the capacitated plant location problem with customer and supplier matching (CLCSM). The product distribution from plants to customers and the material supply from suppliers to plants are considered together. The authors merge a distribution trip and a supply trip into one triangular trip for saving allocation cost. Vehicles from plants visit a customer and a supplier for each trip. The authors provide a heuristic solution procedure based on Lagrangian relaxation. Computational results indicate that the proposed heuristic solution procedure is shown to be efficient yielding optimal or near-optimal solutions for randomly generated instances

How to Improve Food Quality in the Domestic Market: The Role of “Same Line Same Standard Same Quality”—Evidence from a Consumer Choice Experiment in China

Consumers are increasingly concerned about food quality. The “Same line Same standard Same quality” (Santong) program has been implemented to improve food quality in the Chinese domestic market. The Santong program means that exporters are encouraged to produce goods on the same production line, following the same standards and the same quality requirements for both the export target market and the domestic market. Using data collected from an online choice experiment on tomatoes, we examine Chinese consumer preferences and their willingness to pay (WTP) for the Santong claim, export target market quality and organic certification. Three types of export target market, indicating different technical regulations and standards, are considered. Our results show that consumers are willing to pay for the Santong quality claim and for export goods with a target market of “EU”. Furthermore, we also identify the substitution effects between the Santong claim and organic certification. The results of our study provide solutions for both Chinese exporters and the Chinese government to meet the need for a high level of food quality accompanied by domestic consumption upgrade, and achieve the transformation from export to domestic sales. Our results may also provide solutions for other emerging economies, where governments raise the level of food quality in domestic markets and support the domestic sales of exporters after the shock of the coronavirus (COVID-19) pandemic in 2019