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Search Results: 1 - 10 of 755 matches for " Mehrdad Valipour "
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Channel Optimized Distributed Multiple Description Coding
Mehrdad Valipour,Farshad Lahouti
Mathematics , 2011, DOI: 10.1109/TSP.2011.2180903
Abstract: In this paper, channel optimized distributed multiple description vector quantization (CDMD) schemes are presented for distributed source coding in symmetric and asymmetric settings. The CDMD encoder is designed using a deterministic annealing approach over noisy channels with packet loss. A minimum mean squared error asymmetric CDMD decoder is proposed for effective reconstruction of a source, utilizing the side information (SI) and its corresponding received descriptions. The proposed iterative symmetric CDMD decoder jointly reconstructs the symbols of multiple correlated sources. Two types of symmetric CDMD decoders, namely the estimated-SI and the soft-SI decoders, are presented which respectively exploit the reconstructed symbols and a posteriori probabilities of other sources as SI in iterations. In a multiple source CDMD setting, for reconstruction of a source, three methods are proposed to select another source as its SI during the decoding. The methods operate based on minimum physical distance (in a wireless sensor network setting), maximum mutual information and minimum end-to-end distortion. The performance of the proposed systems and algorithms are evaluated and compared in detail.
Sprinkle and Trickle Irrigation System Design Using Tapered Pipes for Pressure Loss Adjusting
Mohammad Valipour
Journal of Agricultural Science , 2012, DOI: 10.5539/jas.v4n12p125
Abstract: Accurate computing of amount of pressure loss is very important in sprinkle and trickle irrigation system design. Not correctly adjusted of pressure loss are causes lack of appropriate performance or failure of sprinkle and trickle irrigation system. By tapered pipes, pressure loss adjusted using increasing or decreasing of pressure head. In this study using HydroCalc software, ability of single and tapered pipes in pressure loss adjusting has been compared. Single and tapered laterals were able to adjusting of pressure loss but single manifolds were not able to achieving to the desired pressure head. In single lateral-tapered manifold system due to the lower pressure loss in laterals, can be use from several types of pipe diameters for manifolds but in tapered lateral-tapered manifold system due to the more pressure loss in laterals, the choice is limited. The best diameters for tapered manifolds with single lateral were 69.2-36.8 mm, 69.2-58.2-36.8 mm, and 58.2-46.0-36.8 mm whereas the best diameters for tapered manifold with tapered lateral were 69.2-46.0-36.8 mm.
Comparison of Surface Irrigation Simulation Models: Full Hydrodynamic, Zero Inertia, Kinematic Wave
Mohammad Valipour
Journal of Agricultural Science , 2012, DOI: 10.5539/jas.v4n12p68
Abstract: Some phenomena such as surface irrigation are so complex that it is very difficult to implement them in nature. For this purpose, simulation models are used. In this study, ability of full hydrodynamic, zero inertia, and kinematic wave models has been investigated in surface irrigation simulation. Using SIRMOD software, their performance has been compared. The results showed that full hydrodynamic and zero inertia models were very powerful in simulation process. For increasing of filed slope until amount of 0.01 full hydrodynamic and zero inertia models had not any difference but for more increasing of S0 due to the increasing of velocity, accuracy of zero inertia model dropped. In full hydrodynamic and zero inertia models for increase in Manning’s roughness coefficient amount of error was increased until n=0.15. After this amount, error remained constant thus n=0.15 determined as critical discharge. Accuracy of kinematic wave model reduced in clay and heavy clay soils, high discharges, high Manning’s roughness coefficient, and basin irrigation. However, in many situations all three models had the same answers and were capable tools to simulating of surface irrigation processes.
Learning and Teaching Ethics through Stories: A Few Examples from the Buddhist Tradition  [PDF]
Mehrdad Massoudi
Creative Education (CE) , 2010, DOI: 10.4236/ce.2010.11004
Abstract: The art of storytelling, similar to poetry, takes us to a different realm, yet always bringing us back to where we are. In many traditional societies, ethical concerns were taught through stories. A few stories from the Buddhist tradition have been selected to convey some basic teachings of the Buddha on ethical issues. This does not mean that these few stories capture the whole of Buddhist ethics. Furthermore, it is understood that similar stories can be found in other traditions, and therefore the same technique can be used in other religions as well. The universalities of these stories provide a means to teach ethics in a multi-cultural context.
Electronic and Structural Properties of Li3AlP2 and Li3AlAs2 from First Principles  [PDF]
Mehrdad Dadsetani, Shirin Namjoo
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.29110
Abstract: A detailed analysis of the electronic and structural properties of the filled tetrahedral semiconductors Li3AlP2 and Li3AlAs2 has been performed, using the full potential linearized augmented plane wave method within the density functional theory. Experimental results about the structural properties, involves the positions of the elements Al and P(As). Since there were not any other efforts about the positions of the Li elements in these compounds, so to our knowledge there was no theoretical study about them till now. In the first step the interactional forces between atoms were minimized. The calculated internal coordinations of atoms agree well with the experimental results. Using these positions we obtained the equilibrium lattice constants, bulk modulus and their pressure derivative. In the second step the electronic properties of Li3AlP2 and Li3AlAs2 have been studied. The study of total and partial electronic DOS indicate the main contribution of DOS consists of P(As) 3p(4p) and P(As) 3s(4s) states. Our band structure calculation verifies that Li3AlP2 is an indirect gap semiconductor with a value of about 2.36 eV between valance band maximum occuring at H point and conduction band minimum occuring at Г point; though the difference between the direct (2.38 eV) and indirect (2.36 eV) is very small. We also found that Li3AlAs2 is a direct band gap (1.49 eV) in the center of BZ.
Determination of Tritium Concentration in Heavy Water  [PDF]
Reza Pourimani, Mehrdad Aghamohammadi
World Journal of Nuclear Science and Technology (WJNST) , 2014, DOI: 10.4236/wjnst.2014.43022
In this work, tritium concentration was determined in different D2O enrichment in heavy water samples. Samples were prepared from Arak Heavy Water Production Plant. Tritium concentration was determined utilizing liquid scintillation detector (LSC) system based on β-decay of tritium isotope. In this work instead of simple distillation, the azeotropic distillation method was used. Absorbed spectra and fluorescence spectra were registered by Shimadz spectrometer UV-2100 model and fluorescence spectrometer LS50B model respectively. Tritium concentration was obtained from 1.75 ± 0.80 up 6.16 ± 1.01 Bq/L for 0.35% to 77.50% enrichment of D2O concentration in heavy water samples. Coefficient correlation between tritium concentration and D2O concentration in heavy water R2 = 0.853 was derived. For 99.8% enriched D2O in heavy water, deviation was observed from direct line that caused decreasing of R2.
GIScience for Sustainable Development  [PDF]
Mehrdad Jafari Salim
Journal of Geographic Information System (JGIS) , 2017, DOI: 10.4236/jgis.2017.94030
Abstract: Due to the importance of development and its impact on our life, in this paper we are going to elaborate on the Sustainable Development and its related issues. In the following, due to the essential role that GIScience can play on the success trend of Sustainable Development, GIScience will be defined and its importance will be discussed as an effective tool in its logical procedure of Sustainable Development. The decision making support systems—using Geo-information and spatial data—is merging increasingly into other disciplines design and techniques day by day. So It would be worth investigation on the technical aspects of sustainable development and its consideration in projects development in general, throughout the literature review and SD requirements. The successful sustained achievement will depend on clear “political” answerability for its reliability and local regulatory environment. It should be in harmony with the additional superior prescription and ruling at the national or international levels by the use and utilization of national spatial data infrastructure. The paper will ends up with a set of suggested practices in the development of Spatial Data Infrastructure (SDI).
3D Spatial Information Intended for SDI: A Literature Review, Problem and Evaluation  [PDF]
Mehrdad Jafari Salim
Journal of Geographic Information System (JGIS) , 2017, DOI: 10.4236/jgis.2017.95033
Abstract: In this paper, first we are going to discuss briefly the importance of 3D information, and its application because of the Increasing demand for detailed information about real world objects and phenomena including altimetry and planimetry data (X, Y, Z), then we will explain in short the available methods for 3D measurement. It’s important to note that the Information collection by itself cannot define and sufficiently provide all the necessary actions to be taken in order to get them accessible and useful for users. The data management and establishment of a proper and reliable DBMS and finally a GIS system at the same time are vital crucial in the course of 3D application that will be discussed throughout the paper. The existing drawbacks and elements needed to be considered for the cartographic presentation are the key issues in three-dimensional world visualization. The elaboration on the 3D information and its knowledge transfer to the users in a SDI framework as well as the requirement recognition of beneficiary organizations will be the next step in this paper and the most probable problems will be studied in this stage. At the final stage, we’ll come up with conclusion, warnings and recommendation.
Impact of Mechanical and Biological Watershed Treatments on Surface Runoff  [PDF]
Mehrdad Safaei, Akram Mahan
Open Journal of Geology (OJG) , 2018, DOI: 10.4236/ojg.2018.89053
Abstract: Floods are common types of water-related natural hazards that cause not only destruction and loss of lives but also erosion and sedimentation. Soil and water conservation (SWC) techniques such as mechanical treatments (placing check dams) and biological treatments (vegetation restoration) are being applied to reduce the velocity of runoff and mitigate the impact of floods. In this research, we evaluated four different SWC scenarios to see how the watershed responds to those watershed treatments. We calibrated and validated a rainfall-runoff model to simulate the impact of biological and mechanical treatments on peak discharge and volume of the runoff in Bishebone watershed in the north of Iran. Simulation of peak discharge for before and after watershed treatments for floods with return periods of 2 to 100 years shows that, the combination impact of mechanical and biological treatments on floods with return period of 100 years is 6.95 to 9.94 percent. Results also show that the impact of mechanical treatments on floods with higher return periods is relatively more than that of shorter return periods.
Distributed Relay Beamforming in Cognitive Two-Way Networks: SINR Balancing Approach  [PDF]
Seyed Hamid Safavi, Mehrdad Ardebilipour
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2012, DOI: 10.4236/ijcns.2012.510070
Abstract: In this paper, we study the problem of distributed relay beamforming for a bidirectional cognitive relay network which consists of two secondary transceivers and K cognitive relay nodes and a primary network with a transmitter and receiver, using underlay model. For effective use of spectrum, we propose a Multiple Access Broadcasting (MABC) two-way relaying scheme for cognitive networks. The two transceivers transmit their data towards the relays and then relays retransmit the processed form of signal towards the receiver. Our aim is to design the beamforming coefficients to maximize quality of service (QoS) for the secondary network while satisfying tolerable interference constraint for the primary network. We show that this approach yields a closed-form solution. Our simulation results show that the maximum achievable SINR improved while the tolerable interference temperature becomes not strict for primary receiver.
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