There has been significant progress in the area of short-term scheduling of batch processes, including the solution of industrial-sized problems, in the last 20 years. The main goal of this paper is ...to provide an up-to-date review of the state-of-the-art in this challenging area. Main features, strengths and limitations of existing modeling and optimization techniques as well as other available major solution methods are examined through this paper. We first present a general classification for scheduling problems of batch processes as well as for the corresponding optimization models. Subsequently, the modeling of representative optimization approaches for the different problem types are introduced in detail, focusing on both discrete and continuous time models. A comparison of effectiveness and efficiency of these models is given for two benchmarking examples from the literature. We also discuss two real-world applications of scheduling problems that cannot be readily accommodated using existing methods. For the sake of completeness, other alternative solution methods applied in the field of scheduling are also reviewed, followed by a discussion related to solving large-scale problems through rigorous optimization approaches. Finally, we list available academic and commercial software, and briefly address the issue of rescheduling capabilities of the various optimization approaches as well as important extensions that go beyond short-term batch scheduling.
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•Integrated system based on solar chimney, wind energy, and hybrid desalination.•Pumped hydro system for supply of electricity and freshwater in absence of sunlight/wind.•Hybrid ...desalination driven by stored heat and wind turbine electricity.•Use of brine for electricity production implementing PRO technology.•Enhanced overall efficiency compared to single solar chimney by multisystem approach.
This paper studies the viability of utilizing an integrated system to yield electricity and freshwater, with solar chimney and wind energy as its leading technologies. An initial analysis is performed to evaluate the electricity generation and heat absorption by the storage system of the solar chimney. Moreover, thermal and membrane-based desalination technologies are included in a cascaded manner to produce freshwater, utilizing the heat source of the solar chimney thermal storage. In addition, a Pressure-Retarded Osmosis subsystem is incorporated to use the discharged brine from the desalination systems, creating an additional electrical output by recovering brine energy. A wind power plant is added for generating more power while satisfying the demand of the multisystem. For energy storage purposes, a pumped hydro system is implemented to store freshwater and meet electrical and water demand without interruption. As a result, the integrated system, including a 5 × 3.4 MW wind farm, presents an overall energetic efficiency of 52.53% during the discharge of the water tank, and 52.51% while storing the water. These efficiencies are significantly higher than a stand-alone solar chimney (0.44%) dedicated to electricity generation only.
Objective
Recurrent aphthous stomatitis (RAS) is a condition that affects 20% of the world population and is characterized by painful ulcers in the oral mucosa. So far, the epidemiology and risk ...factors of RAS have been infrequently studied. Our objective was to determine whether sleep‐related factors are related to the occurrence of RAS in the first prospective study carried out on this topic.
Methods
A cohort of 11210 Spanish students, 13–17 years old, was followed up for one year. Sleep disorders were assessed at baseline using a standard validated questionnaire.
Results
We detected 2655 new cases of RAS with a total of 287,262 person‐week of follow‐up. Subjects with high (4th quartile) Insomnia Index showed an incidence rate ratio (IRR) of RAS of 1.29 (95% confidence interval (CI) 1.15–1.45), while subjects with high Hypersomnia Index presented an IRR of 1.42 (95% CI 1.26–1.61). A high score of sleep‐related phenomena was also associated with an increased IRR: 1.53 (95% CI 1.37–1.69). Adolescents with high level of sleep satisfaction were at lower risk of RAS: 0.88 (95% CI 0.77–1.01).
Conclusion
These findings suggest that sleep disorders are moderately associated with RAS in adolescents.
This study analyzes the possibility to use the wind’s kinetic energy to produce electricity in Northern Qatar for the natural gas processing industry. An evaluation of the wind potentiality is ...performed based on a thorough analysis of parameters such as wind speed and direction, temperature, atmospheric pressure, and air density. In addition, based on the measured parameters, a commercial wind turbine is selected, and a case study is presented in order to quantify the energy that a wind farm could produce and its environmental benefits. Furthermore, an economical assessment is made to quantify the repercussions that it could produce if this wind farm substitutes a fraction of the energy demand (within the oil and gas field) that is currently generated by traditional hydrocarbons. The results indicate that the environmental parameters, led by a 5.06 m/s wind speed mean, allow the production of wind energy in the area with an annual CO2 savings of 6.813 tons in a 17 MW wind power plant. This enables Qatar to reduce its internal oil and gas consumption. As a result, the amount of hydrocarbon (natural gas) saved could be used for exportation purposes, generating a positive outcome for the economy with a cost savings of about 3.32 million US$ per year through such a small size wind power plant. From the energy production point of view, the natural parameters enable a single wind turbine to produce an average of 6995.26 MWh of electricity. Furthermore, the wind farm utilized in the case study is capable of generating an average of 34.976 MWh in a year.
•Classification of scheduling problems.•Summary of industrial requirements for scheduling.•Review of existing scheduling optimization methods, including heuristics, metaheuristics and constraint ...programming.•Lessons learned and success stories on real industrial scheduling implementations.•Future challenges for industry in the area of planning and scheduling.
This paper gives a review on existing scheduling methodologies developed for process industries. Above all, the aim of the paper is to focus on the industrial aspects of scheduling and discuss the main characteristics, including strengths and weaknesses of the presented approaches. It is claimed that optimization tools of today can effectively support the plant level production. However there is still clear potential for improvements, especially in transferring academic results into industry. For instance, usability, interfacing and integration are some aspects discussed in the paper. After the introduction and problem classification, the paper discusses some lessons learned from industry, provides an overview of models and methods and concludes with general guidelines and examples on the modeling and solution of industrial problems.
This paper analyzes the influence of large bank shareholders on the terms of bank loans for a sample of 12,045 loans to 3,290 borrowers from 45 countries over the period 2004–2013. We investigate the ...effects of bank control over bank loan terms during the global financial crisis, regardless of whether the bank shareholder is a lender or not. In line with a monitoring effect, the results suggest that firms with bank shareholders that are non‐lenders borrowed at lower interest rates and longer maturities during the period of crisis. However, borrowers paid higher spreads and were offered shorter maturities when they borrowed from banks that are also shareholders. This effect is consistent with banks obtaining private benefits as large shareholders as a consequence of the informational hold‐up problems affecting borrowers.
The VELOUR study showed the benefit of FOLFIRI-Aflibercept (FA) versus FOLFIRI in patients with metastatic colorectal cancer (mCRC) in second-line treatment. However, only 36% of the included ...patients were ≥65 years. Thus, we seek to evaluate the efficacy and safety of FA in the elderly population in the context of routine practice.
We conducted an observational, retrospective, multicenter, observational study of patients ≥70 years with mCRC treated with FA after progression to oxaliplatin chemotherapy in routine clinical practice in 9 hospitals of the GITuD group.
Of 388 patients treated with FA between June 2013 and November 2018, 75 patients ≥70 years were included. The median number of cycles was 10 and the objective response (ORR) and disease control rates (DCR) were 33.8% and 72.0%, respectively. With a median follow-up of 27.1 months, median Progression-free survival (PFS) was 6.6 months and median Overall Survival (OS) was 15.1 months. One third fewer metastasectomies were performed in the ≥75 years' subgroup (24 vs. 52%, p = 0.024) and more initial FOLFIRI dose reductions (68 vs. 36%, p = 0.014). ORR (23.8% vs. 38.3%), DCR (42.8% vs. 85.1%), and PFS (4 vs. 7.8 months; p = 0.017) were significantly less, without difference in OS (9.9 vs. 17.1 months; p = 0.129). The presence of prior hypertension (HT) (PFS 7.9 vs. 5.7 months, p = 0.049) and HT ≥ grade 3 during treatment (PFS 7.6 vs. 6.6 months, p = 0.024) were associated with longer PFS. The most frequent grade 3/4 adverse events were: asthenia (21.3%), neutropenia (14.7%), and diarrhea (14.7%). 57.3% required FOLFIRI dose reduction; 34.7% of aflibercept, including discontinuation (5.3% and 18.7%, respectively).
FA combination is effective in patients ≥70 years. The occurrence of HT is predictive of efficacy. Close monitoring of toxicity and initial dose adjustment is recommended.
The present study analyzes the wind energy potential of Qatar, by generating a wind atlas and a Wind Power Density map for the entire country based on ERA-5 data with over 41 years of measurements. ...Moreover, the wind speeds’ frequency and direction are analyzed using wind recurrence, Weibull, and wind rose plots. Furthermore, the best location to install a wind farm is selected. The results indicate that, at 100 m height, the mean wind speed fluctuates between 5.6054 and 6.5257 m/s. Similarly, the Wind Power Density results reflect values between 149.46 and 335.06 W/m2. Furthermore, a wind farm located in the selected location can generate about 59.7437, 90.4414, and 113.5075 GWh/y electricity by employing Gamesa G97/2000, GE Energy 2.75-120, and Senvion 3.4M140 wind turbines, respectively. Also, these wind farms can save approximately 22,110.80, 17,617.63, and 11,637.84 tons of CO2 emissions annually.
•Continuous-time approach for scheduling of multi-source pipeline systems.•Parallel batch injections and simultaneous product deliveries to multiple terminals.•The problem goal is to minimize flow ...restart and pump switching costs.•Detailed scheduling of pumping and batch-cut operations is provided.•Specific flow-rate ranges for each pipeline segment are easily managed.
Pipeline networks are the shippers’ first choice for carrying large volumes of refined petroleum products from oil refineries to distant distribution terminals. Optimization approaches for solving the pipeline scheduling problem proceed in two hierarchical stages: the aggregate and the detailed planning steps. The aggregate plan determines the batch sizes, the sequence of batch injections, and the allocation of batches to customers. The subsequent stage refines the aggregate plan to find the detailed schedule of batch input and output operations. This paper presents a mixed-integer linear programming (MILP) formulation for the detailed scheduling of multi-source pipelines that accounts for parallel batch injections and simultaneous product deliveries to multiple terminals. It overcomes a critical drawback of previous models that assume single source configurations. Modeling multi-source pipeline networks is a great challenge, requiring a completely revised approach. The new model finds cost-effective solutions with remarkable efficiency.
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