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Search Results: 1 - 10 of 10504 matches for " Hosseini-Ara "
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Stability analysis of carbon nanotubes based on a novel beam model and its comparison with Sanders shell model and molecular dynamics simulations
Hosseini-Ara, R.;Mirdamadi, H. R.;Khademyzadeh, H.;Mostolizadeh, R.;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2012, DOI: 10.1590/S1678-58782012000200004
Abstract: we study the effects of small-scale parameter on the buckling loads and strains of nanobeams, based on nonlocal timoshenko beam model. however, the lack of higherorder boundary conditions leads to inconsistencies in critical buckling loads. in this paper, we apply a novel approach based on nonlocal timoshenko kinematics, strain gradient approach and variational methods for deriving all classical and higher-order boundary conditions as well as governing equations. therefore, closed-form and exact critical buckling loads of nanobeams with various end conditions are investigated. moreover, the dependence of buckling loads on the small-scale parameter as well as shear deformation coefficient is studied using these new boundary conditions. then, numerical results from this new beam model are presented for carbon nanotubes (cnts). they illustrate a more accurate buckling response as compared to the previous works. furthermore, the critical strains are compared with results obtained from molecular dynamic simulations as well as sanders shell theory and are found to be in good agreement. results show that unlike the other beam theories, this model can capture correctly the small-scale effects on buckling strains of short cnts for the shell-type buckling. moreover, the value of nonlocal constant is calculated for cnts using molecular dynamic simulation results.
Stroke and Cardiovascular Disease among Women  [PDF]
Hengameh Hosseini
Health (Health) , 2015, DOI: 10.4236/health.2015.714203
Abstract: Stroke falls under the umbrella of cardiovascular disease (CVD), which is the number one killer of Americans. CVD, including stroke and heart disease, takes about 267,000 women’s lives every year [1]. In the present study, a health risk assessment of a population of women residing in North-eastern Pennsylvania was conducted to provide an estimate of vulnerability to stroke on the basis of medical history, genetic predisposition, and other lifestyle factors. Using the Health Belief model of Rosenstock, Strecher, and Becker [2] and the stage model of Prochaska, Diflemente, and Norcross [3], a health promotion plan was developed to address the needs of that population. An evaluation of risks that can and cannot be modified is developed to help people understand the basic lifestyle changes that could be made to prevent CVD, which includes stroke. An action plan was developed to lower the risk of stroke among women based on their individual needs and to raise awareness throughout the United States. Individuals should take the essential precautions for their personal cases. This will substantially lower the risk of CVD, especially stroke, among women.
Secure Cognitive Radio Communication for Internet-of-Things: Anti-PUE Attack Based on Graph Theory  [PDF]
Azar Hosseini, Bahman Abolhassani, Arezoo Hosseini
Journal of Computer and Communications (JCC) , 2017, DOI: 10.4236/jcc.2017.511003
Abstract: Internet of Things (IoT) paradigm with strong impact on future life will be interconnected through Cognitive Radio Networks (CRNs). CRNs with Ubiquitous trait are highly promising to achieve interference-free and on-demand services. CRs are able to sense the spectral environment, to detect unoccupied bands, and to use them for signal transmissions. This opportunity encourages malicious Users to surpass CRs by Primary User Emulation (PUE) attack and use vacant spectrums. This paper proposes an unsupervised algorithm to distinguish CRs from PUs regardless of static and mobile user. Employing K-means and graph theory are coincident in our algorithm to improve detection outcomes. The edge of graph corresponding to the relation between signals is used and the result of comparison the signal properties is exposed to different clusters. The Receiver Operating Characteristic (ROC) and Detection Error Tradeoff (DET) of our proposed algorithm prove our claim.
Transmission over Cognitive Radio Channel with Novel Secure LT Code  [PDF]
Elham Hosseini, Abolfazl Falahati
Communications and Network (CN) , 2013, DOI: 10.4236/cn.2013.53023

With the increasing of communication applications in recent years, the demand for radio spectral resources has increased significantly. Cognitive radio scenario was proposed to improve spectrum efficiency in wireless communication systems. In cognitive radio network, it is essential that control information is sent securely and reliably. Ensuring the trustworthiness of the transmitting of spectrum sensing information is important in the CR networks since spectrum sensing directly affects spectrum management and incumbent coexistence. In this paper, the first secondary link channel model is presented, then a secure LT Code is proposed to be compatible with presented channel model and acquires good QoS. As we may know, LT code overcomes packet loss when the channel of the SU is reclaimed by PU. In the new proposed combined encoding and ciphered block, a LT code matrix is used to generate a symmetric cryptographic key. Thus, less complexity observed in the processing computation. Besides, cryptographic key is not sent over the channel. As a result, an attacker has no way to eavesdrop the key unless he is prepared to consider all possible key combinations. This replaced block supplies secure controlling channel and increases spectrum efficiency too.

A Study of Water Supercooling  [PDF]
Amir Gholaminejad, Reza Hosseini
Journal of Electronics Cooling and Thermal Control (JECTC) , 2013, DOI: 10.4236/jectc.2013.31001

The objective of this paper is to investigate water supercooling. Supercooling occurs when a liquid does not freeze although its temperature is below its freezing point. In general, supercooling is an unstable condition and occurs under special conditions. The parameters that influence supercooling stability and probability of occurrence include freezer temperature and water’s initial temperature. In this paper, it is shown that with a freezer temperature range of -3 to -8, supercooling is most likely to happen and is independent of the water’s initial temperature. Furthermore, as the freezer temperature decreases, the probability of nucleation increases, causing instant freezing. Finally, it is concluded that the Mpemba effect, in which initially hot water freezes faster than initially cold water, is due to the supercooling instability in initially hot water in which nucleation agents are more active.

Evaluation of Water Distribution Jointed Pipe Networks under Transient Ground Motions  [PDF]
Alireza Boorboor, Mahmood Hosseini
Open Journal of Civil Engineering (OJCE) , 2015, DOI: 10.4236/ojce.2015.52019
Abstract: In this study, a new method is proposed to evaluate the seismic behavior of buried jointed water pipeline networks subjected to wave propagation. First, using finite element method and solid elements, different kinds of currently used connections in the network are modeled, and their nonlinear behavior in all directions is obtained. Second, a 950-meter long network consisting of ductile iron pipes segments of 6-meter length and springs characterizing the connections, are modeled using beam elements. Three-component displacement record of the Tabas earthquake is applied to the network considering the time lag between support inputs, and the nonlinear soil-pipe interaction. The record is applied once in North-South direction and once in East-West direction with different wave propagation velocities. Results of interest such as stress values and rotations at various points of the network are then obtained, and critical points are introduced in each direction. Results show that the points other than the critical ones at the network intersections remain elastic.
Sensitivity Analysis of Buried Jointed Pipelines Subjected to Earthquake Waves  [PDF]
Alireza Boorboor, Mahmood Hosseini
Open Journal of Earthquake Research (OJER) , 2015, DOI: 10.4236/ojer.2015.42007
Abstract: In this study, a number of nonlinear time-history dynamic analyses are conducted on a part of Tehran water distribution network to investigate its functionality during transient large ground motions. The network is of 950-meter length, consisting of ductile iron pipes segments of 6-meter length. Pipes are modeled using beam elements and springs characterize the connections. Considering the time lag between support inputs, and the nonlinear soil-pipe interaction, by scaling the amplitude of the Tab as earthquake record, incremental dynamic analysis is carried out on the network in two orthogonal directions and the sensitivity of the network response is examined. Furthermore, the effects of variations in soil damping and soil spring stiffness are also studied in the network analysis. Finally the effect of changes in angle between incoming wave and pipeline is considered on a simplified network. Results show that the points other than critical ones at network intersections remain almost intact and when the angle of incidence is 30 degrees the stress and rotation peak.
Aware Diffusion: A Semi-Holistic Routing Protocol for Wireless Sensor Networks  [PDF]
Kamil Samara, Hossein Hosseini
Wireless Sensor Network (WSN) , 2016, DOI: 10.4236/wsn.2016.83004
Abstract: Routing is a challenging task in Wireless Sensor Networks (WSNs) due to the limitation in energy and hardware capabilities in WSN nodes. This challenge prompted researchers to develop routing protocols that satisfy WSNs needs. The main design objectives are reliable delivery, low energy consumption, and prolonging network lifetime. In WSNs, routing is based on local information among neighboring nodes. Routing decisions are made locally; each node will select the next hop without any clue about the other nodes on the path. Although a full knowledge about the network yields better routing, that is not feasible in WSNs due to memory limitation and to the high traffic needed to collect the needed data about all the nodes in the network. As an effort to try to overcome this disadvantage, we are proposing in this paper aware diffusion routing protocol. Aware diffusion follows a semi-holistic approach by collecting data about the available paths and uses these data to enforce healthier paths using machine learning. The data gathering is done by adding a new stage called data collection stage. In this stage, the protocol designer can determine which parameters to collect then use these parameters in enforcing the best path according to certain criteria. In our implementation of this paradigm, we are collecting total energy on the path, lowest energy level on the path, and hop count. Again, the data collected is designer and application specific. The collected data will be used to compare available paths using non-incremental learning, and the outcome will be preferring paths that meet the designer criteria. In our case, healthier and shorter paths are preferred, which will result in less power consumption, higher delivery rate, and longer network life since healthier and fewer nodes will be doing the work.
Difference Sets of Null Density Subsets of N  [PDF]
Dawoud Ahmadi Dastjerdi, Maryam Hosseini
Advances in Pure Mathematics (APM) , 2012, DOI: 10.4236/apm.2012.23027
Abstract: Let , and for any , . If is positive, then B is considered as a large set with . Its difference set has both high density and rich structure. The set with is also relatively large and it is a long standing conjecture that like sets with positive upper density they have arithmetic progression of arbitrary length. Here we show their difference set may not be substantial; for any there exists such that and .
A Fuzzy Logic Model to Predict the Bioleaching Efficiency of Copper Concentrates in Stirred Tank Reactors  [PDF]
Ali Ahmadi, Mohammad Raouf Hosseini
International Journal of Nonferrous Metallurgy (IJNM) , 2015, DOI: 10.4236/ijnm.2015.41001
Abstract: Multiplicity of the chemical, biological, electrochemical and operational variables and nonlinear behavior of metal extraction in bioleaching environments complicate the mathematical modeling of these systems. This research was done to predict copper and iron recovery from a copper flotation concentrate in a stirred tank bioreactor using a fuzzy logic model. Experiments were carried out in the presence of a mixed culture of mesophilic bacteria at 35° C, and a mixed culture of moderately thermophilic bacteria at 50° C. Input variables were method of operation (bioleaching or electrobioleaching), the type of bacteria and time (day), while the recoveries of copper and iron were the outputs. A relationship was developed between stated inputs and the outputs by means of “if-then” rules. The resulting fuzzy model showed a satisfactory prediction of the copper and iron extraction and had a good correlation of experimental data with R-squared more than 0.97. The results of this study suggested that fuzzy logic provided a powerful and reliable tool for predicting the nonlinear and time variant bioleaching processes.
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