The complex problems in the real world, an increase in competition among producers, the advancements in equipment and manufacturing products, the high cost of factory equipment and, etc., have led to ...the production structure change from a centralized structure to a decentralized one. In recent years, distributed systems have become increasingly important. So in order to adapt to market competition and to respond quickly to changing market demand, there is a need to study this problem. An important aspect of planning in a distributed environment is decentralized production. In such cases, it becomes more important to consider the problem of distributed scheduling. In this regard, this paper provides a systematic literature review on the multi-factory scheduling problems in the past eleven years and report the research gaps. To this end, first, the related research was classified based on the shop environments. Then, after reviewing the existing papers and summarizing them, future researches and emerging research fields of the multi-factory scheduling problem are reported. This review indicates that future research should focus on open shop production environments. The results also show only 4% of the papers focus on the virtual alliance. Therefore, researchers need to consider the virtual alliance in the production network and investigate the participation and competition between the partners in such network. Studying the topic of Industry 4.0 in multi-factory scheduling and subsequently investigating the related topics such as information sharing and real-time data are also the new trends in this field. Considering the complex series–parallel structures in the multi-factory production and defining objective functions related to environmental issues such as reducing pollutants and noise are other suggestions for future studies.
The ever-changing and dynamic market environment requires applying job shop systems based on real-time data. The establishment of physical-virtual systems in the production process has led to the ...emergence of intelligent factories. Compared with those employing traditional production methods, such factories manufacture products with higher quality, higher production speed, and other economic benefits. Regarding the virtual connections of factories, events such as the arrival of new jobs, and machine breakdowns, are identified by Radio Frequency Identification System between different production units, and related decisions are made quickly and carefully. In this intelligent job shop scheduling, it is assumed that independent factories create virtual production networks in which, each factory focuses on its own interests. Regarding the importance of this issue in today’s industry, this research explores the real-time scheduling problem in multi-agent production networks distributed in smart factories. Since this problem is a combination of static scheduling and real-time scheduling, a bi-objective model of mixed-integer linear programming is first developed. An approach is then proposed to solve the dynamic real-time scheduling problem. In addition, a learning-based memetic algorithm for solving large-size bi-objective instances is proposed due to the NP-hardness of the considered problem. Afterward, the results of the proposed algorithm are compared with the hybrid Pareto-based tabu search algorithm. The computational results show that in large-size instances, the proposed algorithm outperforms the competing algorithm.
Purpose
Reducing the mean age of puberty onset in recent years has crucial public health, clinical, and social implications. This study aimed to evaluate the serum levels of appetite-related peptides ...(leptin, ghrelin, nesfatin-1, and orexin-A) and anthropometric data in girls with premature thelarche (PT).
Methods
We enrolled 44 girls aged 4–8 years diagnosed with PT and 33 age-matched healthy girls as controls. The demographic data of the girls were obtained using a questionnaire. Anthropometric data were measured and fasting blood samples were collected.
Results
Body weight, height, body mass index (BMI), body fat mass, and basal metabolic rate (BMR) were higher in the PT group than in the control group (
p
< 0.05). Serum leptin (
p
< 0.001), nesfatin-1 (
p
= 0.001), and orxein-A (
p
< 0.001) levels were significantly higher in the PT group than in healthy controls. However, there were no significant differences in the serum ghrelin levels between the groups (
p
> 0.05). The results of multivariate logistic regression revealed that serum leptin level (OR (95% CI): 42.0 (10.91, 173.06),
p
< 0.001), orexin-A (OR (95% CI): 1.14 (1.04, 1.24),
p
= 0.006), and BMI for age z-score (OR (95% CI): 6.97 (1.47, 33.4),
p
= 0.014) elevated the risk of incidence of PT at 4–8 girls.
Conclusion
These results suggest that in addition to serum leptin levels, serum orexin-A and nesaftin-1 can take part in the initiation of PT. Few studies have investigated the relationship between nesfatin-1 and orexin-A levels and age at onset of puberty; hence, it should be a subject for future studies.
Display omitted
•Linseed oil-based resins were synthesized via a two-step procedure of epoxidation and carbonation reactions.•The resins were cured with diethylenetriamine to form non-isocyanate ...polyhydroxy-urethane (NIPHU) networks.•The mechanical and anti-corrosion properties of the NIPHU samples were evaluated.•The results showed proper mechanical properties of NIPHU samples with different carbonation wt%.•The EIS results revealed that corrosion resistance of NIPHU.
In this study, a bio-resource resin was synthesized via epoxidation and carbonation of linseed oil (LO) in acidic conditions, and then in the presence of tetra ‐ n ‐ butyl ammonium bromide (TBAB) and under purging of CO2 gas, respectively. The synthesized resins were characterized using FTIR spectroscopy, NMR analysis, and titration method. The resins were cured with diethylenetriamine to form non-isocyanate polyhydroxy-urethane networks. Rheometry analysis and DSC were utilized for determining the proper time and temperature of the curing process. The physical and mechanical properties of the mild steel coated samples were evaluated using various techniques. Finally, the corrosion resistance of the coated samples was assessed via Electrochemical Impedance Spectroscopy (EIS) and the results were compared with commercial polyurethane-based coated samples.
The characterization tests confirmed the formation of epoxy and cyclo-carbonate groups as a result of the epoxidation process and carbonation reaction of LO, respectively. The various tests showed the appreciation of the mechanical properties of the coating samples with different carbonation weight percentages. The results revealed the improvement of adhesion and hardness properties and reduction of the flexibility of the coating samples with increasing the conversion % of carbonation. As the carbonation content increases, more hydroxyl groups were formed in the final polyhydroxy-urethane structure due to the reaction of the cyclo-carbonate with the amine, resulting in increased adhesion strength and mechanical properties of the polymer. EIS study revealed increasing of the anti-corrosion properties first and then decreasing it by increasing the percentage of carbonation. The 75% carbonated sample revealed the best corrosion performance, which was comparable with PU-based coated samples.
In this paper, a novel mathematical model is developed for the distributed multi-agent network scheduling problem in a dynamic job shop environment with availability constraints and new job arrivals. ...In a dynamic collaborative-competitive environment, a number of factories with independent ownership are merged to form a multi-agent production network in which each production agent, despite participation, seeks to optimize its own objective function as a primary priority. To minimize the makespan and the total energy consumption, the ε-constraint approach is used. Since the problem is NP-hard, a memetic algorithm based on a non-dominated sorting genetic algorithm-II and local search are proposed. Finally, the proposed algorithm is compared with a hybrid Pareto-based tabu search algorithm (HPTSA). The obtained results show that in large-size instances, our proposed algorithm outperforms the HPTSA.
Performance status is an important prognostic tool in cancer. In oncology, the Eastern Cooperative Oncology Group (ECOG) measure is commonly used. Patient-reported functional status (PRFS) is an ...emerging method that allows patients to provide an estimate of their function; however, there is limited information about its prognostic significance. The aim of this study was to compare the predictive validity of functional status as reported by patients and physicians in relation to the observed survival after a new cancer diagnosis.
This was a retrospective, population-based study using observational data of newly diagnosed patients in Ontario, Canada. We included patients who had both PRFS and ECOG recorded on the same day during an outpatient cancer clinic visit between March 2013 and March 2018. The dataset was randomly divided into 60% training and 40% validation cohorts. One-year survival was estimated by modelling clinical characteristics with PRFS, with ECOG, and alone.
In total, 13 045 patients met the inclusion criteria. Covariates were similar at baseline for both training and validation datasets. PRFS and ECOG scores were statistically significant predictors of overall survival. Higher PRFS and ECOG scores were both associated with inferior survival, hazard ratio = 1.71 (P < 0.0001) and hazard ratio = 1.90 (P < 0.0001), respectively. Models that included either PRFS or ECOG scores outperformed the model with clinical characteristics only. C statistics were 0.836, 0.839 and 0.811, respectively.
PRFS adds to survival modelling and is equally predictive as the ECOG scale. PRFS may be used instead of ECOG in clinical or research settings for survival estimation.
•Patient-reported performance status is an emerging method to assess functionality.•Paired patient- and physician-reported performance status were included in a model.•This model aims to predict survival in newly diagnosed cancer patients.•Both scales improved the modelling ability to predict survival by a similar amount.•This patient-reported outcome might be used instead of the physician's scale.
Varieties of Roman domination II Chellali, M.; Jafari Rad, N.; Sheikholeslami, S. M. ...
AKCE international journal of graphs and combinatorics,
09/2020, Letnik:
17, Številka:
3
Journal Article
Recenzirano
Odprti dostop
In this work, we continue to survey what has been done on the Roman domination. More precisely, we will present in two sections several variations of Roman dominating functions as well as the signed ...version of some of these functions. It should be noted that a first part of this survey comprising 9 varieties is published as a chapter book in “Topics in domination in graphs” edited by T.W. Haynes, S.T. Hedetniemi and M.A. Henning. We recall that a function is a Roman dominating function (or just RDF) if every vertex u for which f(u) = 0 is adjacent to at least one vertex v for which f(v) = 2. The Roman domination number of a graph G, denoted by is the minimum weight of an RDF on G.
The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) as a new human coronavirus has begun spreading over Wuhan City/China in December 2019, and then spread rapidly worldwide, causing ...pneumonia called COVID-19. Up to now, the scientists have extensively attempted to find effective vaccines and drugs for treatment of coronavirus infections. To this end, various pharmaceutical agents are undergoing the clinical studies to assess their potency and efficacy against COVID-19. Based on the new findings, the U.S. food and drug administration (FDA) has issued an emergency use authorization for remdesivir as an effective anti-viral for remedying the hospitalized COVID-19 patients. Recently, the European medicines agency has authorized the use of remdesivir for the treatment of COVID-19. Remdesivir as a nucleotide prodrug exhibits broad-spectrum antiviral activities against RNA viruses. In this short review, we have rendered a brief overview of discovery and synthesis for remdesivir.
PDF
