Nonlinear consolidation of soft clays subjected to cyclic loading - Part I: theory

Yazdani, Hessam,Toufigh, Mohammad Mohsen Techno-Press 2012 Geomechanics & engineering Vol.4 No.4

In this paper, utilizing void ratio-effective stress and void ratio-permeability relationships, a system of two nonlinear partial differential equations is derived to predict the consolidation characteristics of normally consolidated (NC) and overconsolidated (OC) soft clays subjected to cyclic loading. A developed feature of the coefficient of consolidation containing two key parameters is emerged from the differential equations. Effect of these parameters on the consolidation characteristics of soft clays is analytically discussed. It is shown that the ratios between the slopes of e-$log{\sigma}^{\prime}$ and e-log k lines in the NC and OC states play a major role in the consolidation process. In the companion paper, the critical assumptions made in the analytical discussion are experimentally verified and a numerical study is carried out in order to examine the proposed theory.

Nonlinear consolidation of soft clays subjected to cyclic loading - Part II: Verification and application

Yazdani, Hessam,Toufigh, Mohammad Mohsen Techno-Press 2012 Geomechanics & engineering Vol.4 No.4

In the companion paper, the nonlinear consolidation of soft clays subjected to cyclic loading was analytically investigated. This paper reports the results of an experimental program conducted to verify some critical assumptions made in the analytical study. It, also, includes a numerical study carried out to examine the capability of the proposed theory to determine the consolidation characteristics of soft clays subjected to cyclic loading. Results show that the permeability of the soft clays does not significantly change during the cyclic loading. It is also shown that, compared to the Terzaghi's solution for a linear clay, the inherit nonlinearity of the clay tends to decrease the degree of consolidation due to the smaller rate of dissipation in the excess pore water pressure.

A comparative study of stored arterial versus venous blood collected using the acute normovolemic hemodilution method in coronary artery bypass grafting patients in Iran

Mansouri Mojtaba,Yazdani Alireza,Masoumi Gholamreza,Mirmohammadsadeghi Mohsen,Mirmohammadsadeghi Amir 대한중환자의학회 2023 Acute and Critical Care Vol.38 No.3

Background: In the present study, arterial and venous blood was collected from patients who were candidates for elective coronary artery bypass grafting (CABG); the blood was stored for 28 days and cellular, biomechanical, and hematological changes in blood were compared to determine whether stored arterial blood is superior to stored venous blood. Methods: The present follow-up comparative study included 60 patients >18 years of age, with hemoglobin >14 mg/dl and ejection fraction >40% who were candidates for CABG. After induction of anesthesia, 250 ml of arterial or venous blood was drawn from patients (arterial blood group and venous blood group). Laboratory blood samples were taken at specified times from the collected blood and re-injected into the patients after CABG. Results: Significant differences were observed in pH, partial pressure of carbon dioxide (PCO2), partial pressure of oxygen (PO2), bicarbonate (HCO3), and glucose values at several time points between the groups. Other parameters such as urea and creatinine did not show any significant differences between the groups. Conclusions: Twenty-eight days of storage can have a negative effect on some of the cellular, biochemical, and hematological components of arterial and venous blood; however, the quality of stored arterial blood and venous blood does not differ significantly.

Optimum design of a sliding mode control for seismic mitigation of structures equipped with active tuned mass dampers

Hussein Eliasi,Hessam Yazdani,Mohsen Khatibinia,Mehdi Mahmoudi 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.81 No.5

The active tuned mass damper (ATMD) is an efficient and reliable structural control system for mitigating the dynamic response of structures. The inertial force that an ATMD exerts on a structure to attenuate its otherwise large kinetic energy and undesirable vibrations and displacements is proportional to its excursion. Achieving a balance between the inertial force and excursion requires a control law or feedback mechanism. This study presents a technique for the optimum design of a sliding mode controller (SMC) as the control law for ATMD-equipped structures subjected to earthquakes. The technique includes optimizing an SMC under an artificial earthquake followed by testing its performance under real earthquakes. The SMC of a real 11-story shear building is optimized to demonstrate the technique, and its performance in mitigating the displacements of the building under benchmark near- and far-fault earthquakes is compared against that of a few other techniques (proportional-integral-derivative [PID], linear-quadratic regulator [LQR], and fuzzy logic control [FLC]). Results indicate that the optimum SMC outperforms PID and LQR and exhibits performance comparable to that of FLC in reducing displacements.

Effects of Work-Related Stress on Work Ability Index among Iranian Workers

Vahid Gharibi,Hamidreza Mokarami,Abrahim Taban,Mohsen Yazdani Aval,Kazem Samimi,Mahmood Salesi 한국산업안전보건공단 산업안전보건연구원 2016 Safety and health at work Vol.7 No.1

Background: Work Ability Index (WAI) is a well-known and valid self-report tool that has been widely used in various studies to identify and avoid early retirement and work-related disability. Nevertheless, very few studies have been carried out to evaluate work ability in Iran. We aimed to investigate the WAI and the effect of work-related stress on it among Iranian workers. Methods: A cross-sectional, descriptive and analytic study was carried out among 449 workers from five working sectors in three big cities of Iran. Work ability and work-related stress were measured using the Persian version of WAI and the Persian version of Health and Safety Executive Stress Indicator Tool. Results: More than a third of the workers surveyed (34.70%) did not have an appropriate level of work ability (WAI < 37). There was a significant correlation between subscales of work-related stress and the mean score of WAI. Furthermore, the variables of body mass index, sleep quality, exercise activity, job tenure, and three subscales of work-related stress including demands, supervisor support, and role were significant predictors of WAI. Conclusion: According to the results of this study, the interventional programs must be focused on improving supervisors support, eliminating ambiguity and conflicts in the role of workers in their job and organization, reducing job demands, improving sleep quality, and increasing exercise activity.

A comparative removal of two dyes from aqueous solution using modified oak waste residues: Process optimization using response surface methodology

Samira Samarbaf,Yaser Tahmasebi Birgani,Mohsen Yazdani,Ali Akbar Babaei 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.73 No.-

In this study, optimization of adsorptive removal of two cationic (methylene blue (MB)) and anionic (acidred 73 (AR 73)) dyes with modified oak waste (MOW) adsorbent was carried out using response surfacemethodology (RSM). The input variables included initial solution pH (2–10), contact time (20–200 min),adsorbent dosage (0.5–2.5 g/L) and initial dyes concentrations (10–90 mg/L). Furthermore, the surfaces ofthe adsorbent were modified with different modifiers tofind the most efficient adsorbent. The obtainedresults of comparative studies on dyes adsorption confirm that sodium hydroxide, compared to othermodifiers, has the highest ability to activate the surfaces of the oak waste (OW) to remove dyes from thesolution. Using NaOH, the removal efficiency of MB and that of AR 73 were obtained to be 96% and 29%,respectively. In addition, results of the optimization study showed that RSM could significantly predictthe experimental data of dyes removal with a high correlation coefficient (0.991 for MB and 0.993 for AR73). The optimum experimental conditions for dyes removal were pH of 6.2, 160 min contact time, 2.0 g/Ladsorbent dosage and 70 mg/L initial dye concentrations. Under this condition, the removal efficiency forMB and AR 73 reached 85.36% and 41.27%, respectively. Ultimately, from thefindings of this study, it isobserved that MOW can be used as an efficient and cost-effective adsorbent for the removal of dyes fromthe contaminated aqueous solution.

Effects of Work-Related Stress on Work Ability Index among Iranian Workers

Gharibi, Vahid,Mokarami, Hamidreza,Taban, Abrahim,Aval, Mohsen Yazdani,Samimi, Kazem,Salesi, Mahmood Occupational Safety and Health Research Institute 2016 Safety and health at work Vol.7 No.1

Background: Work Ability Index (WAI) is a well-known and valid self-report tool that has been widely used in various studies to identify and avoid early retirement and work-related disability. Nevertheless, very few studies have been carried out to evaluate work ability in Iran. We aimed to investigate the WAI and the effect of work-related stress on it among Iranian workers. Methods: A cross-sectional, descriptive and analytic study was carried out among 449 workers from five working sectors in three big cities of Iran. Work ability and work-related stress were measured using the Persian version of WAI and the Persian version of Health and Safety Executive Stress Indicator Tool. Results: More than a third of the workers surveyed (34.70%) did not have an appropriate level of work ability (WAI < 37). There was a significant correlation between subscales of work-related stress and the mean score of WAI. Furthermore, the variables of body mass index, sleep quality, exercise activity, job tenure, and three subscales of work-related stress including demands, supervisor support, and role were significant predictors of WAI. Conclusion: According to the results of this study, the interventional programs must be focused on improving supervisors support, eliminating ambiguity and conflicts in the role of workers in their job and organization, reducing job demands, improving sleep quality, and increasing exercise activity.