Evaluation of monotonic and cyclic behaviour of geotextile encased stone columns

Ardakani, Alireza,Gholampoor, Naeem,Bayat, Mahdi,Bayat, Mahmoud Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.1

Stone column installation is a convenient method for improvement of soft ground. In very soft clays, in order to increase the lateral confinement of the stone columns, encasing the columns with high stiffness and creep resistant geosynthetics has proved to be a successful solution. This paper presents the results of three dimensional finite element analyses for evaluating improvement in behaviour of ordinary stone columns (OSCs) installed in soft clay by geotextile encasement under monotonic and cyclic loading by a comprehensive parametric study. The parameters include length and stiffness of encasement, types of stone columns (floating and end bearing), frictional angle and elastic modulus of stone column's material and diameter of stone columns. The results indicate that increasing the stiffness of encasement clearly enhances cyclic behaviour of geotextile encased stone columns (GESCs) in terms of reduction in residual settlement. Performance of GESCs is less sensitive to internal friction angle and elasticity modulus of column's materials in comparison with OSCs. Also, encasing at the top portion of stone column up to triple the diameter of column is found to be adequate in improving its residual settlement and at all loading cycles, end bearing columns provide much higher resistance than floating columns.

Numerical modeling of soil nail walls considering Mohr Coulomb, hardening soil and hardening soil with small-strain stiffness effect models

Ardakani, Alireza,Bayat, Mahdi,Javanmard, Mehran Techno-Press 2014 Geomechanics & engineering Vol.6 No.4

In an attempt to make a numerical modeling of the nailed walls with a view to assess the stability has been used. A convenient modeling which can provide answers to nearly situ conditions is of particular significance and can significantly reduce operating costs and avoid the risks arising from inefficient design. In the present study, a nailing system with a excavation depth of 8 meters has been modeled and observed by using the three constitutive behavioral methods; Mohr Coulomb (MC), hardening soil (HS) and hardening soil model with Small-Strain stiffness ensued from small strains (HSS). There is a little difference between factor of safety and the forces predicted by the three models. As extremely small lateral deformations exert effect on stability and the overall deformation of a system, the application of advanced soil model is essential. Likewise, behavioral models such as HS and HSS realize lower amounts of the heave of excavation bed and lateral deformation than MC model.

A New Selective Membrane Electrode for Oxalate Based on N,N'-Bis(salicylidene)-2,2-dimethylpropane-1,3-diamine Ni(II)

Ardakani, M.Mazloum,Iranpoor, F.,Karimi, M.A.,Salavati-Niasari, M. Korean Chemical Society 2008 Bulletin of the Korean Chemical Society Vol.29 No.2

A new solvent polymeric membrane electrode, based on N,N'-bis(salicylidene)-2,2-dimethylpropane-1,3-diamine Ni(II) as the ionophore, was designed. The oxalate-selective electrode has the dynamic range between 1.0 10-6 M and 1.0 10-1 M with a Nernstian slope of -28.7 1.0 mV per decade. The detection limit was 6.3 10-7 M. The proposed electrode revealed good selectivities for oxalate over a variety of other anions and could be used in a pH range of 2.0-7.8. The electrode can be used for at least two months without any considerable divergence in potential. The designed electrode was applied as an indicator electrode in the potentiometric determination of oxalate in real samples.

Determination of Salicylate by Selective Poly(vinylchloride) Membrane Electrode Based on N,N'-1,4-Butylene Bis(3-methyl salicylidene iminato) Copper(II)

Mazloum Ardakani, M.,Jamshidpoor, M.,Naeimi, H.,Heidarnezhad, A. Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.8

A new salicylate-selective electrode based on the complex N,N'-1,4-butylene bis(3-methyl salicylidene iminato) copper(II) as the membrane carrier was developed. The electrode exhibits a good Nernstian slope of 59.1 ${\pm}$ 1.0 mV/decade and a linear range of $1.0\;{\times}\;10^{-6}$-1.0 M for salicylate. The limit of detection was $5.0\;{\times}\;10^{-7}$ M. It has a fast response time 10 s and can be used for more than three months. The selective coefficients were determined by the fixed interference method (FIM) and could be used in the pH range 4.5-10.5. It was employed as an indicator electrode for direct determination of salicylate in pharmaceutical samples.

Evaluation of monotonic and cyclic behaviour of geotextile encased stone columns

Alireza Ardakani,Naeem Gholampoor,Mahdi Bayat,Mahmoud Bayat 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.1

Stone column installation is a convenient method for improvement of soft ground. In very soft clays, in order to increase the lateral confinement of the stone columns, encasing the columns with high stiffness and creep resistant geosynthetics has proved to be a successful solution. This paper presents the results of three dimensional finite element analyses for evaluating improvement in behaviour of ordinary stone columns (OSCs) installed in soft clay by geotextile encasement under monotonic and cyclic loading by a comprehensive parametric study. The parameters include length and stiffness of encasement, types of stone columns (floating and end bearing), frictional angle and elastic modulus of stone column’s material and diameter of stone columns. The results indicate that increasing the stiffness of encasement clearly enhances cyclic behaviour of geotextile encased stone columns (GESCs) in terms of reduction in residual settlement. Performance of GESCs is less sensitive to internal friction angle and elasticity modulus of column’s materials in comparison with OSCs. Also, encasing at the top portion of stone column up to triple the diameter of column is found to be adequate in improving its residual settlement and at all loading cycles, end bearing columns provide much higher resistance than floating columns.

A Late Sasanian Hoard from Orumiyeh

( Azadeh Ardakani ) 계명대학교 실크로드중앙아시아연구원 2017 Acta Via Serica Vol.2 No.2

Proper Management for Morbid Iatrogenic Retroperitoneal Barium Insufflation

Jalal Vahedian-Ardakani,Shahram Nazerani,Amir Saraee,Ali Sarmast,Ehsan Saraee,Mohammad Reza Keramati 대한대장항문학회 2014 Annals of Coloproctolgy Vol.30 No.6

A barium enema is a diagnostic and therapeutic procedure commonly used for colon and rectum problems. Rectal perforation with extensive intra- and/or extraperitoneal spillage of barium is a devastating complication of a barium enema that leads to a significant increase in patient mortality. Due to the low number of reported cases in recent scientific literature and the lack of experience with the management of these cases, we would like to present our treatment approach to a rare case of retroperitoneal contamination with barium, followed by its intraperitoneal involvement during a diagnostic barium enema. Our experience with long-term management of the patient and the good outcome will be depicted in this paper.

Fuzzy sliding‐mode control of a human arm in the sagittal plane with optimal trajectory

Fateme Fotouhi Ardakani,Ramin Vatankhah,Mojtaba Sharifi 한국전자통신연구원 2018 ETRI Journal Vol.40 No.5

Patients with spinal cord injuries cannot move their limbs using their intact muscles. A suitable controller can be used to move their arms by employing the functional electrical stimulation method. In this article, a fuzzy exponential sliding‐mode controller is designed to move a musculoskeletal human arm model to track an optimal trajectory in the sagittal plane. This optimal arm trajectory is obtained by developing a policy for the central nervous system. In order to specify the optimal trajectory between two points, two dynamic and static optimal criteria are applied simultaneously. The first dynamic objective function is defined to minimize the joint torques, and the second static optimization is offered to minimize the muscle forces at each moment. In addition, fuzzy logic is used to tune the sliding‐surface parameter to enable an appropriate tracking performance. Simulation results are evaluated and compared with experimental data for upward and downward movements of the human arm.

A Hybrid Adaptive Approach to Improve Position Tracking Measurements

Mostafa K. Ardakani,Seyed Mohammad Fatemi,Hamid Reza Hamidi,Mojtaba Kamaliardakani 한국통신학회 2020 ICT Express Vol.6 No.4

Position tracking of a user or an object has caught many researchers and entrepreneurs’ attention. It has a significant market opportunity as well as applications in daily life such as Earth sciences, intelligent transportation systems, machine control, mapping, surveying, surveillance, tracking, and vehicle testing. The accuracy of different positioning methods depends upon the accuracy of underlying technology and environmental conditions. In this paper, a hybrid adaptive method is developed to enhance the accuracy of positioning. Based on the accuracy and the environments, a coefficient (weight) vector is assigned to the coordinates obtained from INS, GPS, Cellular Network, and Wi-Fi methods. Subsequently, the weighted average method is used to integrate the coordinates to compute the location. The proposed method is tested in an experimental study with different distance settings. The accuracy and robustness of suggested method are validated with GPS and INS hybrids.

Service Design by Identification and Prioritization of Customer Demands in Kano Model

Ali Sarafraz Ardakani,Shima Baradaran Ghannad,Mohammad Mirmohammadi Sadrabad,Hamed Shakerian 대한산업공학회 2018 Industrial Engineeering & Management Systems Vol.17 No.3

Rail Transportation is the best option of transport in many countries of the world. One of the factors that increase the share of rail passenger transportation is developing rail transportation of passenger by increasing level of customer satisfaction in this type of service. The main purpose of this paper is service design by identification and prioritization of customer demands in Kano model. The statistical population consisted of travelers who used the Iran South-East Railway services. To determine the sample size, as there was not any certain statistical test as research requirement, we used the saturated sample, so that we selected samples as long as the opinions became converged. Semi-structured interviews, interviews with experts and a questionnaire for a two-week period in January 2014 were used to collect data. The final questionnaire was compiled and its validity was confirmed after obtaining the expert’s points of view and fixing deficiencies and problems. Cronbach’s alpha coefficient was used to assess the reliability of questionnaire. Descriptive and inferential statistics were used to analyze the obtained information from the questionnaires. Kano model, QFD method in the SPSS and Excel were used for the inferential statistics. Data analysis in the Kano model and QFD method was done in Excel software; and Spss16 software was used to measure the reliability. After identifying the characteristics of service with the help of experts, quality Function Development (QFD) was used to prioritize them and finally, required services has been ranked and proper selection of personnel, upgrade facilities of rail and the exact timing of train schedules are 3 first priority, if first six priorities are done, almost half of the costumers will be satisfied.