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Search Results: 1 - 10 of 14896 matches for " Mohammad Amin Rashidifar "
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Control Application of Piezoelectric Materials to Aeroelastic Self-Excited Vibrations
Mohammad Amin Rashidifar,Darvish Ahmadi
Shock and Vibration , 2014, DOI: 10.1155/2014/509024
Abstract: A method for application of piezoelectric materials to aeroelasticity of turbomachinery blades is presented. The governing differential equations of an overhung beam are established. The induced voltage in attached piezoelectric sensors due to the strain of the beam is calculated. In aeroelastic self-excited vibrations, the aerodynamic generalized force of a specified mode can be described as a linear function of the generalized coordinate and its derivatives. This simplifies the closed loop system designed for vibration control of the corresponding structure. On the other hand, there is an industrial interest in measurement of displacement, velocity, acceleration, or a contribution of them for machinery condition monitoring. Considering this criterion in quadratic optimal control systems, a special style of performance index is configured. Utilizing the current relations in an aeroelastic case with proper attachment of piezoelectric elements can provide higher margin of instability and lead to lower vibration magnitude. 1. Introduction The dependence of mechanical and electrical properties of piezoelectric materials on their application in various materials as patches or layers makes them an appropriate sensor or actuator for vibration control of structures. In sensing situation, the mechanical and creep deformations of structures can be determined by measuring the electrical potential produced in piezoelectric materials. This property is termed the direct property of the piezoelectric material. Then an effective feedback mechanism sends an electric signal to an actuator to keep the vibration of the mechanical system to a minimum. In actuator applications, the inverse piezoelectric effect is used. Recently, this technique is widely used in the active control of vibrations, deformation control of structures, and aerospace industries. This technique has been investigated by research in solid and aeroelastic areas. In solid, Gaudenzi et al. [1] investigated the vibration control of an overhung beam by means of finite element approach based on Euler-Bernoulli beams. They studied state feedback and velocity feedback control of vibration. Moreover, Q. Wang and C. M. Wang [2] implemented vibration control of a beam with piezoelectric patches by taking finite element method into account. They determined an optimized position for an appropriate actuator and the subsequent vibration amplitude of a hinged-hinged beam by applying a feedback control procedure and converting the finite element model into its state space form. Narayanan and Balamurugan [3] studied
Numerical Solution of Nonlinear Integro-Differential Equations with Initial Conditions by Bernstein Operational Matrix of Derivative  [PDF]
Behrooz Basirat, Mohammad Amin Shahdadi
International Journal of Modern Nonlinear Theory and Application (IJMNTA) , 2013, DOI: 10.4236/ijmnta.2013.22018
Abstract:

In this paper, we present a practical matrix method for solving nonlinear Volterra-Fredholm integro-differential equations under initial conditions in terms of Bernstein polynomials on the interval [0,1]. The nonlinear part is approximated in the form of matrices’ equations by operational matrices of Bernstein polynomials, and the differential part is approximated in the form of matrices’ equations by derivative operational matrix of Bernstein polynomials. Finally, the main equation is transformed into a nonlinear equations system, and the unknown of the main equation is then approximated. We also give some numerical examples to show the applicability of the operational matrices for solving nonlinear Volterra-Fredholm integro-differential equations (NVFIDEs).

Searching for quantum speedup in quasistatic quantum annealers
Mohammad Amin
Physics , 2015, DOI: 10.1103/PhysRevA.92.052323
Abstract: We argue that a quantum annealer at very long annealing times is likely to experience a quasistatic evolution, returning a final population that is close to a Boltzmann distribution of the Hamiltonian at a single (freeze-out) point during the annealing. Such a system is expected to correlate well with a proper quantum Monte Carlo simulation. It may also correlate with simulated annealing if at the freeze-out point the quantum energy eigenvalues are close to the classical ones. These correlations are just signatures of equilibration and do not mean that the evolution of the quantum annealer is classical or can be simulated by quantum Monte Carlo. The computation time extracted from such a distribution reflects the equilibrium behavior and therefore provides no information about the underlying quantum dynamics. This makes the search for quantum speedup in suboptimal quantum annealers problematic. We use an open quantum master equation with realistic parameters to illustrate quasistatic evolution in a 16 qubit quantum annealer and discuss its implication for quantum speedup.
Bearing Capacity Assessment of Collapsible Soils Improved by Deep Soil Mixing Using Finite Element Method  [PDF]
Pouya Kavandi, Alireza Firoozfar, Mohammad Amin Hemmati
Open Journal of Geology (OJG) , 2016, DOI: 10.4236/ojg.2016.69079
Abstract: Problematic soils usually cause considerable problems to engineering projects. As an example, soil structure collapse caused by moisture increment or rising underground water level results in huge settlements. This type of problematic soil, named collapsible soil, can cause dramatic problems and should be amended where exists. Today, the use of different techniques for soil reinforcement and soil improvement is widely used to treat soil properties. One of these methods is Deep Soil Mixing (DSM) method. This method becomes more important in the cases of studying and examining collapsible soils. In this research, the settlement of amended collapsible soils, applying deep soil mixing method, is examined. The experiments show that soil amendment using this method, well prevents the settlement of collapsible soils giving rise to bearing capacity.
Analysis of Sleep Window of IEEE802.16m Network Based on State Transition Chain  [PDF]
Mohammad Asif Hossain, Mohammad Imdadul Islam, Mohamed Ruhul Amin
Journal of Computer and Communications (JCC) , 2015, DOI: 10.4236/jcc.2015.312007
Abstract: Energy efficiency plays vital roles in wireless communication system due to the “energy limited battery service” of a mobile station (MS). To ensure longer battery life in WiMAX, a new protocol has been introduced in its IEEE802.16m version. This new sleep mode has extended listening window and adjustable sleep cycle length. In this paper, we analyze the probability of attaining at three states: serving state, state of timer inactivity and silent state in a simplified statistical model using traffic parameters of arrival rate, pdf (probability density function) of interarrival time and its threshold value. Finally we developed a new state transition chain of the above three states of a MS of IEEE802.16m and solved the chain in closed form.
Load Sensitive Power Saving Technique for 4G Mobile Network under Limited User Traffic  [PDF]
Mohammad Asif Hossain, Mohammad Imdadul Islam, Mohamed Ruhul Amin
Communications and Network (CN) , 2016, DOI: 10.4236/cn.2016.82009
Abstract: Power saving is one of the key factors of emerging 4G mobile network as well as in IEEE 802.16e wireless metropolitan area networks (Wireless MAN). An efficient power saving mechanism is the heart for the guarantee of a long operating lifetime for a mobile subscriber station (MS), because MSs are normally driven by rechargeable batteries. It is a vital factor for Base Station (BS) of the same network. One of the most important features of 5G mobile is the extension of battery energy 10 times greater than the present days. In this context, the evaluation of duration of sleep mode of BS or MS based on traffic load of a network is now a new era of research work. In this paper, such analysis has been done based on two statistical models: Poisson’s pdf and Engset pdf. The concept of complete sharing and partitioning of user group of teletraffic engineering is applied to measure the possibility of getting leisure time of BS or MS. Both the traffic models used in the paper are applicable in both limited and unlimited user network, i.e. in micro and fem to cellular network of 4G and 5G.
PC-Based Centralized System for Controlling and Determining Status of Electrical Devices
Mohammad Rohul Amin
Journal of Engineering and Applied Sciences , 2012,
Abstract: At present a world that people prefer automated systems rather than manual systems because of efficient, reliable and timesaving. Since the automated centralized electrical system is very expensive, most of the offices, hotels and industries are still controlling their decentralized electrical systems manually. In case of large organization, these manual decentralized electrical systems are very time consuming for controlling and furthermore the administrator of existing system could not identify the present status (On/Off) of the electrical devices. The proposed system consists of an electronic circuit which interfaces with a computer through the parallel port for timely controlling the electrical devices centrally using the database software. The proposed database software records the transactions about each and every devices, can estimate the total used time for a specific device. It includes internal memory for PC-free operation; control over 4,000 devices at a time; feed-through outlet won t block from plugging in other devices; and provides easy trouble-free connection. This PC-based centralized system is very effective for the home, offices, hotels and industries in terms of cost and time for controlling the electrical devices.
Analysis on the Virtual Local Area Network to Reduce Collision Domain and Manage Broadcast Domain
Mohammad Rohul Amin
Asian Journal of Information Technology , 2012,
Abstract: This is the age of communication technology. Effectively data communication is a big aspect for the business development. The concept of Virtual Local Area Network (VLAN) technology holds the potential for harmonizing many of today s organizational and managerial changes with the structural and technological developments in the network. Despite the promise of this vision, VLAN implementation must solve the real-world problems in order to be financially justified. Organizations those have deployed or are planning to deploy the large numbers of switch ports, dividing the network into the smaller segments to increase the bandwidth per user, can make a very strong case for the VLAN implementation in order to contain the broadcast. This study tries to present an effective solution which will increase the performance of a Local Area Network (LAN). In the real-world, there is a lot of transmission impairments are occurred which hampering the data transmission processes. Collision domain is one of the major problems which decrease the performance of a network. The proposed network tries to reduce the collision domain using the VLAN and also implements the Spanning Tree Protocol (STP) which manages the broadcast storms. For an efficient data transmission purpose, the network administrator needs an effective solution which is scalable and easy to mange depends on the network architecture.
Interactional Feedback and the Impact of Attitude and Motivation on Noticing L2 Form
Mohammad Amin Bassiri
English Language and Literature Studies , 2011, DOI: 10.5539/ells.v1n2p61
Abstract: A number of second language (L2) studies have recently discovered the positive impacts of interactional feedback (IF) in L2 development by connecting the underlying processes such as noticing. The current study followed a two-fold purpose: first to examine the impact of IF on noticing question forms in Iranian L2 classroom context and secondly to investigate the possible effects of motivation and attitude on noting IF. IF was provided to experimental group learners in response to their production problems with question forms. Learners’ noticing was assessed through on-line learning journals, introspective comments while checking with audiotapes, and questionnaire responses. Learners’ motivation was also assessed using Gardner’s (1996) attitude/motivation test. The results point to a positive relationship between IF in the classroom and the learners’ reports about question forms of English. The results also confirmed the existence of a positive correlation between motivation and noticing.
Intonation Patterns and Their Place in Teaching Pronunciation for Azeri-Speaking English language Learners
Mohammad Amin Bassiri
Studies in English Language Teaching , 2013,
Abstract: Although there has always been controversies around the importance of two levels of phonology (segmental and suprasegmental) in language teaching history, today there is a general consensus that both levels of phonology (segmental and suprasegmental) should be taken into consideration to reach the goals of pronunciation instruction. However time shortage is a factor that forces us as teachers to set priorities and be selective of materials that have more crucial role in understanding and being understood than others both in segmental and suprasegmental level. Our touchstone in this way is the degree to which these features affect the comprehensibility of materials. The current study examined the degree to which intonation patterns affect comprehensibility. The results of the study supported the initial prediction that Intonation patterns play no crucial role in pronunciation teaching to impede comprehension.
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