2D numerical modelling of soil-nailed structures for seismic improvement

Panah, Ali Komak,Majidian, Sina Techno-Press 2013 Geomechanics & engineering Vol.5 No.1

An important issue in the design of soil-nailing systems, as long-term retaining walls, is to assess their stability during seismic events. As such, this study is aimed at simulating the dynamic behavior and failure pattern of nailed structures using two series of numerical analyses, namely dynamic time history and pseudo-static. These numerical simulations are performed using the Finite Difference Method (FDM). In order to consider the actual response of a soil-nailed structure, nonlinear soil behaviour, soil-structure interaction effects, bending resistance of structural elements and construction sequences have been considered in the analyses. The obtained results revealed the efficiency of both analysis methods in simulating the seismic failure mechanism. The predicted failure pattern consists of two sliding blocks enclosed by three slip surfaces, whereby the bottom nails act as anchors and the other nails hold a semi-rigid soil mass. Moreover, it was realized that an increase in the length of the lowest nails is the most effective method to improve seismic stability of soil-nailed structures. Therefore, it is recommended to first estimate the nails pattern for static condition with the minimum required static safety factor. Then, the required seismic stability can be obtained through an increase in the length of the lowest nails. Moreover, placement of additional long nails among lowest nails in existing nailed structures can be considered as a simple retrofitting technique in seismic prone areas.

An Efficient Computational Hybrid Filter to the SLAM Problem for an Autonomous Wheeled Mobile Robot

Amir Panah,Homayun Motameni,Ali Ebrahimnejad 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.10

The using of an autonomous wheeled mobile robot (AWMR) that perform diverse processes in a numerous number of applications without human’s interposition in an unknown environment is thriving, nowadays. An AWMR can search the environment, create an adequate map, and localizing itself into this map, by interpreting the environment, autonomously. The FastSLAM is a structure for simultaneous localization and mapping (SLAM) for an AWMR. The correctness and efficiency of the estimation of the FastSLAM often depend on the accurate a previous knowledge of the control and measurement noise covariance matrices. Also, inaccurate previous knowledge may seriously degrade their efficiency. One of the major causes of losing particle manifold is sample impoverishment in the FastSLAM. These cases of the most main problems. This paper presents a robust new method to solve these problems as called Hybrid filter SLAM. In this method, for learning the measurement and control noise covariance matrices for increasing correctness and consistency are utilized Intuitionistic Fuzzy Logic System (IFLS). In order to optimize efficiency of sampling from Cuckoo Search (CS). The results of the simulation and experimental shown that the Hybrid filter SLAM is efficient than the FastSLAM that has less number of computations and good performance for the larger environment.

Study the Rate of Mathematical Skills of Students in Higher Technical Education Center of Guilan in Different Cognitive Scopes

( Hedayat Panah Ahmad ) 한국수학교육학회 2012 수학교육 학술지 Vol.2012 No.1

The aim of this research paper is to study about Guilan University students` skills in mathematics lesson according to Bloom`s recognition compasses. Statistical samples were 241 university students (males and females) from different branches of technical major who answered mathematics questions from whatever they had learned before entering the university. The Exam included 50 multiple choice questions which were designed and classified due to Benjamin Bloom`s recognition compasses, Results show that: a) Students had the best performance in science, understanding (perception) and application, but they had the least performance in evaluation and judgment, analysis and combination. b) Girls had the most performance in understanding (perception) and application compasses but in other compasses, boys had better performance.

Techno-economic Analysis and Life Cycle Impact Assessment for the Valorisation of Kraft Lignin and Low-Voltage Hydrogen Production

Soltani Panah Hamidreza,Jeong Dong Hwi 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.3

This study presents a comparative techno-economic analysis and life cycle impact assessment of hydrogen production from the kraft lignin depolymerization (KLD) with those produced from alkaline electrolysis cell (AEC) and proton exchange membrane electrolysis (PEM). This process happens in a continuous modular fl ow reactor by using the phosphomolybdic acid as a redox-active catalyst and includes depolymerizing the kraft lignin, producing vanillin, acetovanillone, and hydrogen under a low-voltage condition. For the techno-economic analysis, fi rst, the processes were modelled by using the Aspen Plus V12.1 software and then the results were transferred to Aspen Process Economic Analyzer V12 for economic evaluation. In the next step, the life cycle impact assessment was proposed by using the openLCA V1.11.0 software along with the Environmental Footprint database (MID-Point indicator), and 18 impacts were investigated. According to the techno-economic analysis, KLD exhibits a total capital cost that surpasses that of AEC and PEM by more than 18% and 11%, respectively. Furthermore, KLD’s equipment cost exceeds that of AEC and PEM by approximately 0.5% and 7%, respectively, and necessitates additional components. On the other hand, the life cycle assessment revealed that KLD yields lesser environmental impacts than AEC, while PEM exhibits the most exemplary environmental performance.

Students` Field-dependency and Their Mathematical Performance based on Bloom`s Cognitive Levels

( Alamolhodael Hassan ),( Hedayat Panah Ahmad ),( Radmehr Farzad ) 한국수학교육학회 2011 수학교육연구 Vol.15 No.4

Students approach mathematical problem solving in fundamentally different ways, particularly problems requiring conceptual understanding and complicated strategies. The main objective of this study is to compare students` performance with different thinking styles (Field-dependent vs. Field independent) in mathematical problem solving. A sample of 242 high school males and females (17-18 years old) were tested based on the Witkin`s cognitive style (Group Embedded Figure Test) and by a math exam designed in accordance with Bloom`s Taxonomy of cognitive level. The results obtained indicated that the effect of field dependency on student`s mathematical performance was significant. Moreover, field-independent (Fl) students showed more effective performance than field-dependent (FD) ones in math tasks. Male students with H styles achieved higher results compared to female students with FD cognitive style. Moreover, H students experienced few difficulties than FD students in Bloom`s Cognitive Levels. The implications of these results emphasize that cognitive predictor variables (H vs. FD) could be challenging and rather distinctive factor for students` achievement.

Estimating of Soil-Water Characteristic Curve Using Air Permeability

Mohammad Reza Neyshabouri,Panah Mohammadi 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Experimental and Numerical Study of a Seismic Rotating Mass Damper (RMD) in an Isolated Floor

Afshin Kalantari,Reihane Shafie Panah 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.4

Negative stiffness has shown a capable characteristic in reduction of seismic response of structures. In this paper a passive Rotating Mass Damper (RMD) with negative stiffness characteristic, which was conceptually introduced in an earlier study, has been employed experimentally and numerically on an isolated floor to protect the building content during strong ground motions. The equipment was assumed as a rigid block on the isolated floor. The RMD devices force results indicate the negative stiffness characteristic of the damper. It was also observed that the RMD could increase the natural period of the system up to 50 percent without increasing the mass or reducing the stiffness. A numerical model of a seven storey building was employed to investigate the seismic response of the isolation floor in fourth storey. Two RMD models with different specifications and a viscous damper providing 10 percent of critical damping were applied in the study. Seven ground motion records were selected from PEER ground motion database. The time history analysis results indicate that RMD dampers show acceptable performance in terms of reducing both acceleration up to 40% and displacement responses up to 68% simultaneously in comparison with the viscous damper under the applied ground motions. The model was also analyzed employing seven artificial seismic waves. The results in this part also show the capability of the damper model in generating negative stiffness characteristics and a successful performance during excitation.

An experimental study on polymer cathode materials in lead-acid battery energy storage systems

Davoud Jahani,Amin Nazari,Mohammadreza Yazdan Panah,Nader Javani,Fatemeh Moharaminezhad 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.8

The replacement of lead grids with acrylonitrile butadiene styrene (ABS) polymer grids in the negativeelectrode of lead-acid batteries was studied experimentally, while the positive electrode remained unchanged. A polymergrid was activated by nickel plating using a chemical solution, and then coated with chrome and copper conductiveplating. The polymer grid was coated with a layer of lead. Using a lead-coated polymer grid, a 30-amp 12-voltbattery was produced and tested, and the results were compared with a 30-hour production line lead-acid battery. Theresults show that the polymer grid has a strong ability to generate an appropriate voltage in the charge and dischargecycle and create a stable capacity. The results also show the polymer grid weight has decreased significantly (about50%) compared to the conventional lead grid. In this work, the adhesion of a negative paste to the surface of the polymergrid covered with the lead-exposed expand grid was studied, and the results show that the polymer grid canadhere to the negative dough perfectly.

Dynamic response analysis of nanoparticle-nanobeam impact using nonlocal theory and meshless method

Isa Ahmadi,Mohammad Naeim Moradi,Mahdi Davar Panah 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.89 No.2

In this study, the impact response of a nanobeam with a moving nanoparticle is investigated. Timoshenko beam theory is used to model the nanobeam behavior and nonlocal elasticity theory is used to consider the effects of small dimensions. The interaction between the nanoparticle and nanobeam has been described using Lennard-Jones potential theory and the equations are discretized by the radial basis meshless method and a mathematical model is presented for the nanobeamnanoparticle system. Validation of the proposed model is achieved by comparing the obtained natural frequencies with reference values, demonstrating good agreement. Dimensionless frequency analysis reveals a decrease with increasing nonlocal parameter, pointing out a toughening effect in nanobeam. The dynamic response of the nanobeam and nanoparticle is obtained by time integration of equations of motion using Newmark and Wilson- methods. A comparative analysis of the two methods is conducted to determine the most suitable approach for this study. As a distinctive aspect in this study, the analysis incorporates the deformation of the nanobeam resulting from the nanoparticle-nanobeam interaction when calculating the Lennard-Jones force in the nanobeam-nanoparticle system. The numerical findings explore the impact of various factors, including the nonlocal parameter, initial velocity, nanoparticle mass, and boundary conditions.

Prediction of Soil Hydraulic Conductivity at Saturation Using Air Permeability at Any Individual Soil Water Content

Mehdi Rahmati,Mohammad Reza Neyshaboury,Panah Mohammadi 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.12

Several studies aimed at linking hydraulic conductivity at saturation (Kw,s) to air permeability (Ka(θw)) of soil at given water content (θw) since it can be measured more rapidly and nondestructively than Kw,s especially regarding some new in situ technologies for Ka(θw) measurement. Following this, the current research aimed to develop a semi-theoretical relation between Kw,s and Ka(θw) using measured data in 27 soil samples. The Ka(θw) was measured at 12 different θw contents between 1.5 to 1,500 kPa suctions. Applying these measured data, we proposed a semi-theoretical function to predict Kw,s using Ka(θw) as input variable. The results showed that the proposed function was able to predict Kw,s using Ka(θw) at any individual θw content with really high accuracy consisting of R2 = 0.986 and evaluating error (ER) of the 2% between measured and predicted Kw,s. However, the outcomes revealed that Ka(θw) measurement at lower θw contents resulted in greater accuracy for proposed model. The pertinent section of the article applied multivariate linear regression (MLR) to develop pedo-transfer functions (PTFs) to estimate the parameters of the proposed model. The results revealed that the developed PTFs had relatively greater accuracy and reliability showing average determination coefficient (R2) of 0.807 and 0.729 for training and test datasets, respectively. However, more detailed investigation with wide range of soil parameters are needed for more general PTFs development.