High-precision modeling of uplift capacity of suction caissons using a hybrid computational method

Alavi, Amir Hossein,Gandomi, Amir Hossein,Mousavi, Mehdi,Mollahasani, Ali Techno-Press 2010 Geomechanics & engineering Vol.2 No.4

A new prediction model is derived for the uplift capacity of suction caissons using a hybrid method coupling genetic programming (GP) and simulated annealing (SA), called GP/SA. The predictor variables included in the analysis are the aspect ratio of caisson, shear strength of clayey soil, load point of application, load inclination angle, soil permeability, and loading rate. The proposed model is developed based on well established and widely dispersed experimental results gathered from the literature. To verify the applicability of the proposed model, it is employed to estimate the uplift capacity of parts of the test results that are not included in the modeling process. Traditional GP and multiple regression analyses are performed to benchmark the derived model. The external validation of the GP/SA and GP models was further verified using several statistical criteria recommended by researchers. Contributions of the parameters affecting the uplift capacity are evaluated through a sensitivity analysis. A subsequent parametric analysis is carried out and the obtained trends are confirmed with some previous studies. Based on the results, the GP/SA-based solution is effectively capable of estimating the horizontal, vertical and inclined uplift capacity of suction caissons. Furthermore, the GP/SA model provides a better prediction performance than the GP, regression and different models found in the literature. The proposed simplified formulation can reliably be employed for the pre-design of suction caissons. It may be also used as a quick check on solutions developed by more time consuming and in-depth deterministic analyses.

A NEW CHARACTERIZATION OF ALTERNATING AND SYMMETRIC GROUPS

ALAVI, S. H.,DANESHKHAW, A. 한국전산응용수학회 2005 Journal of applied mathematics & informatics Vol.17 No.1

In this paper we prove that the alternating groups A_n, for n = p, p+1, p+2 and symmetric groups $S_n$, for n = p, p+1, where p$\ge$3 is a prime number, can be uniquely determined by their order components. As one of the important consequence of this characterization we show that the simple groups An, where n = p, p+1, P+2 and p$\ge$3 is prime, satisfy in Thompson's conjecture and Shi's conjecture.

Molecular Dynamics Simulations of Hydrogen Bonding in Clathrate Hydrates with Ammonia and Methanol Guest Molecules

Alavi, Saman,Shin, Kyuchul,Ripmeester, John A. American Chemical Society 2015 Journal of chemical and engineering data Vol.60 No.2

<P>We performed molecular dynamics simulations of the ammonia and methanol-based clathrate hydrates with the emphasis on characterizing hydrogen-bonding interactions of these guest molecules with the water lattice. Systems studied include structure II (sII) binary clathrate hydrates of tetrahydrofuran (THF) (large cage, L) + NH<SUB>3</SUB> (small cage, S) and THF (L) + CH<SUB>3</SUB>OH (S), the structure I (sI) pure NH<SUB>3</SUB> (L), pure CH<SUB>3</SUB>OH (L), the binary NH<SUB>3</SUB> (L) + CH<SUB>4</SUB> (S), and binary CH<SUB>3</SUB>OH (L) + CH<SUB>4</SUB> (S) clathrate hydrates. We simulated these clathrate hydrates with the transferable intermolecular potential with four point changes (TIP4P) water potential and the TIP4P/ice water potential to determine the effect of the water potential on the predicted hydrogen bonding of the guest molecules. Simulations show that, despite strongly hydrogen bonding with the framework water molecules, clathrate hydrate phases with NH<SUB>3</SUB> and CH<SUB>3</SUB>OH can be stable within temperatures ranges up to 240 K. Indeed, a limited number of thermodynamic integration free energy calculations show that both NH<SUB>3</SUB> and CH<SUB>3</SUB>OH molecules give more stable guest–host configurations in the large sI clathrate hydrate cages than methane guests. Predictions of hydrogen bonding from simulations with the two different water potentials used can differ substantially. To study the effect of proton transfer from water to the basic NH<SUB>3</SUB> guests, simulations were performed on a binary NH<SUB>3</SUB> + CH<SUB>4</SUB> sI clathrate hydrate where less than 10 % of the ammonia guests in the large cages were converted to NH<SUB>4</SUB><SUP>+</SUP> and a water molecule of the hydrate lattice in the same large cage was converted to OH<SUP>–</SUP>. The small percentage of proton transfer to ammonia guests in the large cages did not affect the stability of the resultant hydrate. The structural perturbations in the lattice that result from this proton transfer are characterized.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jceaax/2015/jceaax.2015.60.issue-2/je5006517/production/images/medium/je-2014-006517_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/je5006517'>ACS Electronic Supporting Info</A></P>

Optimal stiffness distribution in preliminary design of tubed-system tall buildings

Alavi, Arsalan,Rahgozar, Reza Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.6

This paper presents an optimal pattern for distributing stiffness along a framed tube structure through an analytic equation, which may be used during the preliminary design stage. Most studies in this field are computationally intensive and time consuming, while a hand-calculation method, as presented here, is a more suitable tool for sensitivity analyses and parametric studies. Approach in development of the analytic model is to minimize the mean compliance (external work) for a given volume of material. A variational statement of the problem is made, and a specified deformation-profile is obtained as the necessary condition for a minimum; enforcing this condition, stiffness is then computed. Due to some near-zero values for stiffness, the problem is modified by considering a lower bound constraint. To deal with this constraint, the design domain is assumed to be divided into two zones of constant stiffness and constant curvature; and the problem is restated in terms of these concepts. It will be shown that this methodology allows for easy computation of stiffness through an analytic and dimensionless equation, valid in any system of units. To show practicality of the proposed method, a tubed-system structure with uniform stiffness distribution is redesigned using the proposed model. Comparative analyses of the results reveal that in addition to simplicity of the proposed method, it provides a rather high degree of accuracy for real-world problems.

Evidence-based Medicine versus the Conventional Approach to Journal Club Sessions: Which One Is More Successful in Teaching Critical Appraisal Skills?

Mostafa Alavi-Moghaddam,Shahram Yazdani,Fathie Mortazavi,Samira Chichi,Seyed-Mostafa Hosseini-Zijoud 전남대학교 의과학연구소 2016 전남의대학술지 Vol.52 No.2

This study aimed to compare evidence-based medicine (EBM) vs. conventional approachesto journal club sessions in teaching critical appraisal skills in reading papersby emergency medicine residents. This double cut off discontinuation regression quasi-experimental study was conducted among emergency medicine residents. EBM vs. the conventional approach were applied to teach critical appraisal skills for half of theresidents as an experimental group and another half as a control group respectively. Both groups participated in one hour monthly journal club sessions for six months. Before and after the study, all participants were examined by two tests: the Fresno Test(FT) [to evaluate their knowledge about EBM] and the Critical Appraisal Skills Test(CAST) [to evaluate their competency with critical appraisal skills]. The allocation ofthe participants into the experimental or control groups was according to their CASTscores before the study. 50 emergency medicine residents participated. After the study,the scores of both groups in the FT and CAST significantly improved (p<0.01), andthe promotion of scores of the FT and CAST in the experimental group were more thanthat of the conventional group (p<0.0001). The current study indicated that an evidence-based medicine approach in journal club sessions was comparatively more advantageouscompared to the conventional approach in teaching critical appraisal skillsfor reading papers among the residents of emergency medicine.

Efficacy and safety of combined oral iron chelation therapy with deferasirox and deferiprone in a patient with beta-thalassemia major and persistent iron overload

Samin Alavi,Elham Sadeghi,Azin Ashenagar 대한혈액학회 2014 Blood Research Vol.49 No.1

Evaluation of synergistic effect of Chlorella vulgaris and citric acid on oxidative stability of virgin olive oil

Nasireh Alavi,Mohammad-Taghi Golmakani 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.4

Green microalga Chlorella (Chlorella vulgaris) powder was employed as a natural antioxidant in virgin olive oil and its antioxidant activity was compared with those of b-carotene and a-tocopherol during 16 days of accelerated storage. Furthermore, the synergistic effects of Chlorella and citric acid were investigated. The primary, secondary, and total oxidation products of Chlorella samples (with and without citric acid) were lower than those of the control samples. Induction period of Chlorella samples were significantly higher than those of the control, b-carotene, and a-tocopherol samples. Furthermore, carotenoid and chlorophyll contents of Chlorella samples were significantly higher than those of the control samples. These pigments can delay the oxidation process. Using Chlorella and citric acid in combination with each other showed no synergistic effect against the oxidation of virgin olive oil. In conclusion, Chlorella can be affirmed as a natural antioxidant, which extends the shelf life of virgin olive oil.

Optimal stiffness distribution in preliminary design of tubed-system tall buildings

Arsalan Alavi,Reza Rahgozar 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.6

This paper presents an optimal pattern for distributing stiffness along a framed tube structure through an analytic equation, which may be used during the preliminary design stage. Most studies in this field are computationally intensive and time consuming, while a hand-calculation method, as presented here, is a more suitable tool for sensitivity analyses and parametric studies. Approach in development of the analytic model is to minimize the mean compliance (external work) for a given volume of material. A variational statement of the problem is made, and a specified deformation-profile is obtained as the necessary condition for a minimum; enforcing this condition, stiffness is then computed. Due to some near-zero values for stiffness, the problem is modified by considering a lower bound constraint. To deal with this constraint, the design domain is assumed to be divided into two zones of constant stiffness and constant curvature; and the problem is restated in terms of these concepts. It will be shown that this methodology allows for easy computation of stiffness through an analytic and dimensionless equation, valid in any system of units. To show practicality of the proposed method, a tubed-system structure with uniform stiffness distribution is redesigned using the proposed model. Comparative analyses of the results reveal that in addition to simplicity of the proposed method, it provides a rather high degree of accuracy for real-world problems.

Waist Circumference and Spirometric Measurements in Chronic Obstructive Pulmonary Disease

Ali Alavi Foumani,Alireza Jafari,Zahra Abbasi Ranjbar,Ehsan Kazemnezhad Leyli,Shima Ildari,Mohammad Masoud Neyaragh 질병관리본부 2019 Osong Public Health and Research Persptectives Vol.10 No.4

Objectives: The aim of this study was to evaluate whether the waist circumference of patients with chronic obstructive pulmonary disease (COPD), had an impact on lung function. Methods: There were 180 patients with COPD recruited into this prospective cross-sectional study. The age, weight, body mass index and waist circumference (WC) were measured. Spirometry parameters including forced vital capacity (FVC), and forced expiratory volume in the first second (FEV1), were measured and FEV1/FVC calculated. Results: The mean FEV1/FVC in both normal weight and overweight patients, did not statistically significantly correlate with WC. The COPD assessment test, positively correlated with WC (p = 0.031). A positive correlation with body mass index (p < 0.001), smoking (p = 0.027), and global initiative for chronic obstructive lung disease score (p = 0.009), were observed to positively associate with WC. WC, age, C-reactive protein, duration of disease, and gender (male), were observed to be statistically significant risk factors for the severity of COPD. Conclusion: WC was not observed to impact upon lung function in this study but it was a predictive factor for COPD severity in patients.

Hematological malignancies complicating β-thalassemia syndromes: a single center experience

Samin Alavi,Alieh Safarisharari,Elham Sadeghi,Somayeh Amiri 대한혈액학회 2013 Blood Research Vol.48 No.2