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.

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

ILLEGALITY AS AN EXCEPTION TO PRINCIPLE OF AUTONOMY IN DOCUMENTARY LETTERS OF CREDIT; A COMPARATIVE APPROACH

( Hamed Alavi ) 고려대학교 법학연구원 2016 Korea University Law Review Vol.20 No.-

The case of Sztejn V. J. Henry Schroder banking Corporation and recognition of fraud exception was starting point to erode the absolute application of autonomy principle in documentary letters of credit at global level. More than seventy years after recognition of fraud exception, complicated process of international trade gave rise to other possible exceptions to autonomy principle including illegality, unconscionability, nullity and recklessness of beneficiary. Despite the fact that principle of illegality has age old application in different legal systems to make contracts against statue, good faith and public policy as unenforceable, its application to documentary letters of credit is not completely clear. Clearly, the LC or bank guarantee which has been issued on an illegal basis will be considered unenforceable even without involving the autonomy principle. However, problem will occur where underlying contract is illegal as autonomy principle separates the credit from the underlying contract. In current paper, author tries to tap on problem of illegality in underlying contract and its effect on enforceability of the credit in different jurisdictions. In doing so, this paper endeavours to provide answers to following questions: what is the legal nature of illegality and what are preconditions for its application in the framework of documentary letters of credit? How do different national laws regard illegality as a possible exception process of LC transaction? And what are existing criticisms against recognition of illegality defence as an exception to autonomy principle in documentary letters of credit system?

phytosynthesis of zinc oxide nanoparticles and its antibacterial, antiquorum sensing, antimotility, and antioxidant capacities against multidrug resistant bacteria

Mehran Alavi,Naser Karimi,Iraj Salimikia 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.72 No.-

It was used green biosynthesized zinc oxide (ZnO) NPs (average diameter of 50–60 nm) with abilities of antibacterial against sensetive and MDR bacteria including Escherichia coli ATCC 25922, Serratia marcescens ATCC13880, Pseudomonas aeruginosa ATCC 27853 (gram negative), and Staphylococcus aureus ATCC 43300 and Staphylococcus epidermidis ATCC 12258 (gram positive). High reduction in biofilm formation was 63.43% (0.562 ± 0.015) and 62.88% (0.582 ± 0.025) at 100 μg/mL concentration against control for S. epidermidis and P. aeruginosa respectively. In conclusion, this investigation illustrated simple green synthesis of ZnO NPs with suitable advantages of antioxidant, antibacterial, anti-biofilm, anti-QS activities, and also anti-swarming motility against MDR bacteria.

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

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.