Artificial Intelligence Approach for Seismic Control of Structures

Abstract In the first part of this research, the utilization of tuned mass dampers in the vibration control of tall buildings during earthquake excitations is studied. The main issues such as optimizing the parameters of the dampers and studying the effects of frequency content of the target earthquakes are addressed. Abstract The non-dominated sorting genetic algorithm method is improved by upgrading generic operators, and is utilized to develop a framework for determining the optimum placement and parameters of dampers in tall buildings. A case study is presented in which the optimal placement and properties of dampers are determined for a model of a tall building under different earthquake excitations through computer simulations. Abstract In the second part, a novel framework for the brain learning-based intelligent seismic control of smart structures is developed. In this approach, a deep neural network learns how to improve structural responses during earthquake excitations using feedback control. Abstract Reinforcement learning method is improved and utilized to develop a framework for training the deep neural network as an intelligent controller. The efficiency of the developed framework is examined through two case studies including a single-degree-of-freedom system and a high-rise building under different earthquake excitation records. Abstract The results show that the controller gradually develops an optimum control policy to reduce the vibrations of a structure under an earthquake excitation through a cyclical process of actions and observations. Abstract It is shown that the controller efficiently improves the structural responses under new earthquake excitations for which it was not trained. Moreover, it is shown that the controller has a stable performance under uncertainties

Chest CT Scan or RT-PCR: Which One is Appropriate for Screening of COVID-19 among the Surgical Patients in the Preoperative Period? A Case Report

Coronavirus disease 2019 (COVID-19) is associated with high morbidity and mortality. It has been a significant impact on the surgical care of the patients. There is still no consensus on elective surgeries under time epochs with national partial control of the disease. The objective is to report the clinical course of the surgical patient who was eventually diagnosed with COVID-19 despite preoperative screening. A 69 years old woman was referred to the surgical ward for elective low anterior resection (LAR). The complete preoperative workup was performed with acceptable results. Reverse transcriptase-polymerase chain reaction (RT-PCR) of SARS-COV-2 was not performed because the patient was asymptomatic and the surgical procedure was scheduled during the time of country's partial pandemic control; the nadir of the curve in daily reported COVID-19 patients. Following the surgery, the patient’s clinical status was stable for about 8 hours; however, the patient became anuric and hypotensive, receiving a variety of treatments for a list of differential diagnosis, including fresh lung CT scan and RT-PCR test; both of the latter were positive for COVID-19. Despite COVID-19 management and respiratory support, the patient died on day 15 of hospitalization. It seems that postponing elective surgeries if possible and general screening with RT-PCR in situations where delay in surgeries is not possible, are rationale strategies for surgical management of the patients during the COVID-19 pandemic, even when daily situation of the pandemic seems stable

Passive Control of Tall Buildings Using Distributed Multiple Tuned Mass Dampers

The vibration control of the tall building during earthquake excitations is a challenging task due to their complex seismic behavior. This paper investigates the optimum placement and properties of the Tuned Mass Dampers (TMDs) in tall buildings, which are employed to control the vibrations during earthquakes. An algorithm was developed to spend a limited mass either in a single TMD or in multiple TMDs and distribute them optimally over the height of the building. The Non-dominated Sorting Genetic Algorithm (NSGA – II) method was improved by adding multi-variant genetic operators and utilized to simultaneously study the optimum design parameters of the TMDs and the optimum placement. The results showed that under earthquake excitations with noticeable amplitude in higher modes, distributing TMDs over the height of the building is more effective in mitigating the vibrations compared to the use of a single TMD system. From the optimization, it was observed that the locations of the TMDs were related to the stories corresponding to the maximum modal displacements in the lower modes and the stories corresponding to the maximum modal displacements in the modes which were highly activated by the earthquake excitations. It was also noted that the frequency content of the earthquake has significant influence on the optimum location of the TMDs

The Influence of Fasting and Energy Restricting Diets on IGF-1 Levels in Humans: A Systematic Review and Meta-Analysis

Background: Fasting and energy restricting diets have a potential means of delaying or preventing the onset of a range of age-related metabolic and neoplastic diseases. Consistently at the centre of this effect appears to be a significant reduction in circulating IGF-1 levels. The aim of the current systematic review and meta-analysis was to determine the influence of fasting and energy restriction on IGF-1 levels in human subjects. Methods: A comprehensive systematic search was conducted from onset of the database to February 2019 in Embase, MEDLINE/PubMed, and SCOPUS to identify randomized clinical trials that investigating the impact of fasting or energy restriction circulating IGF-1 levels. Effect size was reported as weighted mean difference (WMD) and 95 confidence intervals (CI) using a random-effects models. Subgroup analysis was performed to identify the probable source of heterogeneity among trials. Results: Total pooling of fasting and energy restriction randomised controlled trials in WMD analysis revealed no significant effect on circulating IGF-1 levels (WMD: �16.41 ng/ml, 95 CI: �35.88, 3.07). Sub grouped analysis fasting regimens appeared to substantially reduce IGF-1 (WMD: -28.87 ng/ml, 95 CI: �43.69, �14.05, I 2 = 00), energy restricting regimens failed to do the same (WMD: -10.98 ng/ml, 95 CI: �33.08, 11.11, I 2 = 90). Within this final subgrouping, it was observed that only energy restriction regimens of 50 or greater of normal daily energy intake were capable of significantly reducing IGF-1 levels (WMD: -36.57 ng/ml, 95 CI: �59.19, �13.95, I 2 = 00). Finally, a meta regression were noted in which the percentage restriction of daily energy intake inversely correlated with plasma IGF-1 levels (p = 0.04). Conclusion: This study uncovered that fasting significantly reduced levels of IGF-1, while energy restriction diets were successful only when intake was reduced by 50 or more. © 2019 Elsevier B.V