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Search Results: 1 - 10 of 360 matches for " Pedram Ghaderi "
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A Study on Instantaneous Time-Frequency Methods for Damage Detection of Nonlinear Moment-Resisting Frames
Ehsan Darvishan,Gholamreza Ghodrati Amiri,Pedram Ghaderi
Shock and Vibration , 2014, DOI: 10.1155/2014/523675
Abstract: Most of the civil structures exhibit nonlinear hysteresis behavior during earthquakes. However, detection of damage in these structures is a challenging issue due to successive change in structural characteristics during a seismic excitation. The current paper presents a promising approach for damage detection of nonlinear moment frames. First, several instantaneous time-frequency methods including Hilbert-Huang transform, direct quadrature, Teager energy operator, and higher-order energy operator are investigated as signal processing tools and the most appropriate method is selected using an outlier analysis. Next, a procedure is proposed based on time-frequency analysis in conjunction with clustering to find damage extension in moment frames under a seismic excitation using frequency, amplitude, and energy damage measures. A probabilistic approach is implemented to investigate capability of the procedure for different ground motion records using incremental dynamic analysis. Results show that frequency is not an appropriate feature to detect damage in nonlinear structures. 1. Introduction During an earthquake many civil structures undergo damages. Therefore, it is important to ensure serviceability and safety of the structures after a seismic excitation. Today, nondestructive evaluation techniques (NDE) are widely utilized for health monitoring and damage detection of structures. At present, current practical methods are based on visual inspection, CT scanning, ultrasonic, stress waves, acoustic emission, and so forth [1]. However, these local damage detection methods are effective only for small structures or structural members. Recently, global vibration-based techniques have attracted researchers since they can solve the problem of large and complicated structures. These methods include power spectrum, Fourier transform, spectrum analysis, and cepstrum analysis [2]. The main drawback of these procedures is that they cannot trace time-varying nature of signals due to their fixed functions. Instead, time-frequency methods are effective tools for analyzing nonstationary signals which makes them appropriate for health monitoring and fault detection of civil, mechanical, and aerospace systems [3]. Doebling et al. [4] and also Fan and Qiao [5] gave a detailed review of vibration-based damage detection methods. An experimental investigation was conducted on a three-story shear building by Xu and Chen [6]. They studied applicability of empirical mode decomposition (EMD) to detect sudden change in structural stiffness. Yang et al. [7] tried to extract
Homotopy Perturbation Method for Solving Moving Boundary and Isoperimetric Problems  [PDF]
Sara Ghaderi
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.35062
Abstract: In this paper, homotopy perturbation method is applied to solve moving boundary and isoperimetric problems. This method does not depend upon a small parameter in the equation. homotopy is constructed with an imbedding parameter p, which is considered as a “small parameter”. Finally, we use combined homotopy perturbation method and Green’s function method for solving second order problems. Some examples are given to illustrate the effectiveness of methods. The results show that these methods provides a powerful mathematical tools for solving problems.
Variational Iterative Method Applied to Variational Problems with Moving Boundaries  [PDF]
Fateme Ghomanjani, Sara Ghaderi
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.35061
Abstract: In this paper, He’s variational iterative method has been applied to give exact solution of the Euler Lagrange equation which arises from the variational problems with moving boundaries and isoperimetric problems. In this method, general Lagrange multipliers are introduced to construct correction functional for the variational problems. The initial approximations can be freely chosen with possible unknown constant, which can be determined by imposing the boundary conditions. Illustrative examples have been presented to demonstrate the efficiency and applicability of the variational iterative method.
The Study of Personality Traits and Demographic Characteristics of Prisoners with Psychopathic Personality Disorder in Comparison with Ordinary Prisoners in Sample of Tehran Prisoners, Tehran, Iran.
D Ghaderi
Qom University of Medical Sciences Journal , 2012,
Abstract: Background and Objectives: Most conducted research about psychopathy has been done among Western countries' prisoners and it has remained unclear whether these findings are applicable in other contexts. The aim of this is to survey personality traits and demographic characteristics of prisoners with psychopathic personality disorder in comparison with ordinary prisoners in sample of Tehran prisoners. Methods: This study was done based on descriptive method. 202 prisoners were selected among Ray City prisoners in Tehran and the applied method was sample available. All prisoners completed Hare (PCL-SV) psychopathic personality disorder checklist and five personality traits Questionnaire, McCare and Costa (Neo-FFI). Data were analyzed by Pearson correlation, Regression, and T student for independent groups. Results: The prevalence of psychopathy disorder among prisoners of this group was reported 10.89. Statistical analysis by Pearson correlation test, regression analysis and T student independent groups, represent a significant positive relationship between Psychopaty and extraversion (p=1%) and a significant negative relationship between openness and Psychopaty (p=5%), agreeableness and conscientiousness (p=1%), respectively. No relationship was found between psychopathy, and neurosis. Furthermore, results indicated that, in comparison with non-psychopathic prisoners, psychopathic prisoners were more neurosis and extraversion, however, they showed low level of openness, agreeableness and conscientiousness. Conclusion: According to the findings, psychopathic disorder and five personality traits are related. Therefore, futher studies in the field of examined variables can provide more information.
The role of Phytophthora cactorum in decline of hydroponically- grown strawberry and evaluation of relative resistance of strawberry cultivars to it
F. Ghaderi
Journal of Science and Technology of Greenhouse Culture , 2012,
Abstract: Phytophtora crown- and root- rot is one of the important soil-borne diseases of strawberry grown in hydroponic culture. Plant roots affected by root and crown rot show yellowish and decline symptoms and the plant perishes and dies gradually. To identify the factor responsible for strawberry crown rot, some samples were taken from infected plants. The samples were washed with tap water for 1-2 hr, blotted dry and plated on CMA. Phytophtora fungus was separated from infected tissue. Based on morphological characteristics and temperature requirement, the pathogen was identified as Phytophthora cactorum. Comparison of crown and root colonization and percent of dead seedlings showed that Selva, Aliso and Gavita cultivars had the most and the least resistance, respectively, but Kameroseh showed immune response to Phytophthora cactorum.
On Coarse Graining of Information and Its Application to Pattern Recognition
Ali Ghaderi
Computer Science , 2014, DOI: 10.1063/1.4906011
Abstract: We propose a method based on finite mixture models for classifying a set of observations into number of different categories. In order to demonstrate the method, we show how the component densities for the mixture model can be derived by using the maximum entropy method in conjunction with conservation of Pythagorean means. Several examples of distributions belonging to the Pythagorean family are derived. A discussion on estimation of model parameters and the number of categories is also given.
Humanitarian Law's Dimensions on Application Mass Destruction's Weapons
Behrouz Ghaderi
International Journal of Nations Research , 2018, DOI: -
Abstract: Articles 22-27 of the declaration of human rights are devoted to the subject of economic, social and cultural rights. In this articles, using mass destruction's weapons actually seems a kind of abuse from the defenses' right, and the International Court of Justice with silence about the Prohibition of Nuclear Weapons' function as a legitimate defense somehow has justified the use or function of other mass destruction weapons. Organization for the prohibition of chemical weapons and the envisaged organs in the treaty, enjoy a lot of authority so that, in the event of misconduct or violation by any member that in his commitment to the treaty, create doubt and hesitate. The organization may recommend collective actions, including sanctions, against the mischief government to other member states. However, although rules of war law have not made significant progress, but government contractual obligations in the case of war, it is also not so trivial as a source of war law. In this article is tried using descriptive-analytical method, to be investigated humanitarian dimension based on mass destruction weapons. And evaluated the most important challenge of this plan with international law and with the aim of examining different aspects from the perspective of human rights and international law.
Weighted Sum Rate Maximization in OFDM Based Cooperative Cognitive Radios: A Joint Optimization Approach  [PDF]
Pedram Johari, Vahid Tabataba Vakili
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2012, DOI: 10.4236/ijcns.2012.55035
Abstract: Improving utilization of the radio spectrum is the main goal of Cognitive Radio Networks (CRN). Recent studies made use of cooperative relay technology in cognitive networks, to increase transmission diversity gain. In this paper we consider an OFDM based cooperative cognitive network with a pair of Source-Destination nodes as the primary user (PU), and a pair of Source-Destination nodes—which is assisted with a relay—as the secondary (cognitive) user (SU). Both primary and secondary users share a same spectrum. In a two hop transmission, the source transmits in the first hop, and the half-duplex relay decodes the message, re-encodes and forwards it to the destination in the second hop on a different subcarrier. The cognitive network obeys an underlay paradigm where the SU is allowed to transmit simultaneously with PU, while its power is limited such that the interference caused for PU does not exceed a defined temperature. Under this constraint, a joint subcarrier pairing and power allocation is proposed for SU to maximize its weighted sum rate. The problem is transformed to a convex optimization problem and solved in the dual domain. Then an algorithm to achieve feasible solutions is used based on the optimization results. Through extensive simulations, we compare the spectrum utilization of the proposed approach with the existing ones, and show that interestingly the proposed method improves the weighted sum rate of SU.
Solving the Optimal Control of Linear Systems via Homotopy Perturbation Method  [PDF]
Fateme Ghomanjani, Sara Ghaderi, Mohammad Hadi Farahi
Intelligent Control and Automation (ICA) , 2012, DOI: 10.4236/ica.2012.31004
Abstract: In this paper, Homotopy perturbation method is used to find the approximate solution of the optimal control of linear systems. In this method the initial approximations are freely chosen, and a Homotopy is constructed with an embedding parameter , which is considered as a “small parameter”. Some examples are given in order to find the approximate solution and verify the efficiency of the proposed method.
An Improved Method for Seismic Site Characterization with Emphasis on Liquefaction Phenomena  [PDF]
Abbas Abbaszadeh Shahri, Roshanak Rajablou, Abdolvahed Ghaderi
Open Journal of Earthquake Research (OJER) , 2012, DOI: 10.4236/ojer.2012.12002
Abstract: Iran is an active seismic region and frequent earthquakes and because of the active faults, often leads to severe casual-ties caused by structural destruction. Earthquake damage is commonly controlled by three interacting factors, source and path characteristics, local geological and geotechnical conditions and type of the structures. Obviously, all of this would require analysis and presentation of a large amount of geological, seismological and geotechnical data. In this paper, nonlinear geotechnical seismic hazard analysis considering the local site effects was executed and the soil lique-faction potential analysis has been evaluated for the Nemat Abad earth dam in Hamedan province of Iran because of its important socioeconomic interest and its location. Liquefaction susceptibility mapping is carried out using a decisional flow chart for evaluation of earthquake-induced effects, based on available data such as geological, groundwater depth, seismotectonic, sedimentary features, in situ, field and laboratory geotechnical parameters. A series model tests were conducted and then on base of the achieved data the idealized soil profile constructed. A C# GUI computer code “NLGSS_Shahri” was Generate, developed and then employed to evaluate the variation of shear modulus and damping ratio with shear strain amplitude to assess their effects on site response. To verify and validate the methodology, the obtained results of the generated code were compared to several known applicable procedures. It showed that computed output of this code has good and suitable agreement with other known applicable procedures.
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