Sharif Digital Repository

Cooperation among nodes is vital in wireless networks since in such networks nodes depend on each other for routing packets. However, cooperation in such operations consumes nodes recourses such as battery and bandwidth. Therefore, it is necessary to design incentive mechanisms to enforce nodes to forward packets when the source and destination of the packet are other nodes. We study routing in wireless networks from a game theoretic view point. Based on this view, the network consists of greedy and selfish nodes who accept payments for forwarding data for other nodes if the payments cover their individual costs incurred by forwarding data. Also, route falsification attacks are easy to... 

Cooperation among nodes is important in ad hoc networks since in such networks nodes depend on each other for forwarding packets. However, cooperation in such operations consumes nodes energy and recourses. Therefore, it is necessary to design incentive mechanisms to enforce nodes to forward packets when the source and destination of the packet are other nodes in the network. We study routing in ad hoc and wireless networks from a game theoretic view point. Based on this view, the network consists of selfish and greedy nodes who accept payments for forwarding data for other nodes if the payments cover their individual costs incurred by forwarding data. Also, route falsification attacks are... 

Cooperation among nodes is vital in Mobil Ac Hoc Networks (MANETs) since in such networks nodes depend on each other for forwarding and routing packets. However, cooperation in such operations consumes nodes' recourses such as battery and bandwidth. Therefore it is necessary to design incentive mechanisms to enforce nodes to forward packets when the source and destination of the packet are other nodes. In this paper, we present a distributed fair solution to judge, punish and re-admit a selfish node, forcing nodes to cooperate with each other. Our scheme is different from previous ones in that it combines two characteristics that have been separately handled in previous works. The first... 

The heat transfer phenomenon in a vortex engine was investigated. A mixture of butane and propane was used as the fuel in which the mole fraction of butane and propane was 0.2 and 0.8, respectively. A series of tests were conducted in different conditions of oxidizer and fuel mass flow rates for a vortex engine. The tests were categorized into two groups to find the effects of the oxidizer mass flow rate on the flux of radiation heat transfer and convective cooling at a fixed equivalence ratio. The effects of the equivalence ratio on the heat transfer phenomena at a fixed oxidizer mass flow rate are also determined. The results revealed that the rate of radiation heat transfer to the chamber... 

In a vortex engine, oxidizer issues tangentially at the end of the chamber, consequently a cool vortex flows toward the head, being mixed with fuel, a secondary vortex of combustible reactants swirls coaxial with the first vortex to the nozzle exit. Therefore radiation heat transfer from flame to the chamber wall causes to increase wall temperature; meanwhile highly convective coolant flow of outer vortex reduces the wall temperature. In this paper the rate of total heat transfer and radiative heat are measured experimentally and convective cooling is calculated as the difference between the above mentioned quantities. The rate of heat transfer to the chamber wall is calculated using... 

Construction of two haplotypes from a set of Single Nucleotide Polymorphism (SNP) fragments is called haplotype reconstruction problem. One of the most popular computational model for this problem is Minimum Error Correction (MEC). Since MEC is an NP-hard problem, here we propose a novel heuristic algorithm based on clustering analysis in data mining for haplotype reconstruction problem. Based on hamming distance and similarity between two fragments, our iterative algorithm produces two clusters of fragments; then, in each iteration, the algorithm assigns a fragment to one of the clusters. Our results suggest that the algorithm has less reconstruction error rate in comparison with other... 

Natural nanochannels and those used for applied purposes are often several nanometers in diameter and have lengths up to micrometer scales. Since normally no pressure gradient, mechanical force or electrical field is exerted on fluids in these situations, the fluid flow within them is not single-file and can be bidirectional. For this reason, studying the behavior of bidirectional flows in the channels is of paramount importance. In this study, a comprehensive investigation on the straight and non-straight bidirectional water transfer through carbon nanotubes is conducted via extensive molecular dynamics simulations. The results indicate that by changing the length, the diameter and the... 

The application of the solar energy in thermal desalination devices is one of the most beneficial applications of the renewable energies. In this study, a novel solar desalination system is introduced, which is benefited from the undeniable advantages of pulsating heat pipe (PHP) as a fast responding, flexible and high performance thermal conducting device. Results show a remarkable increase in the rate of desalinated water production and the maximum production reaches up to 875mL/(m2.h). However, the optimum water depth in basin and the filling ratio of the PHP are measured 1cm and 40%, respectively  

Today's software systems are more frequently composed from preexisting commercial or non-commercial components and connectors. These components provide complex and independent functionality and are engaged in complex interactions. Component-Based Software Engineering (CBSE) is concerned with composing, selecting and designing such components. As the popularity of this approach and hence number of commercially available software components grows, selecting a set of components to satisfy a set of requirements while minimizing cost is becoming more difficult. This problem necessitates the design of efficient algorithms to automate component selection for software developing organizations. We... 

Many complex networks such as social networks and computer show modular structures, where edges between nodes are much denser within modules than between modules. It is strongly believed that cellular networks are also modular, reflecting the relative independence and coherence of different functional units in a cell. In this paper we used a human curated dataset. In this paper we consider each module in the PPI network as ontology. Using techniques in ontology alignment, we compare each pair of modules in the network. We want to see that is there a correlation between the structure of each module or they have totally different structures. Our results show that there is no correlation... 

Background: Angiogenesis inhibition research is a cutting edge area in angiogenesis-dependent disease therapy, especially in cancer therapy. Recently, studies on anti-angiogenic peptides have provided promising results in the field of cancer treatment. Methods: A non-redundant dataset of 135 anti-angiogenic peptides (positive instances) and 135 non anti-angiogenic peptides (negative instances) was used in this study. Also, 20% of each class were selected to construct an independent test dataset (see Additional files 1, 2). We proposed an effective machine learning based R package (AntAngioCOOL) to predict anti-angiogenic peptides. We have examined more than 200 different classifiers to build... 

Thermal conductivity and phonon transport properties of graphyne nanotubes (GNTs) and conventional carbon nanotubes (CNTs) are studied using nonequilibrium molecular dynamics simulations. The effect of nanotube length on the thermal conductivity and phonon transport transition from a ballistic to a diffusive regime is investigated. It is found that the thermal conductivity is significantly higher for CNTs in comparison to that of GNTs across the entire ballistic-diffusive transport range. Among GNTs, β- and γ-GNTs demonstrated the lowest and highest thermal conductivities, respectively. In addition, ultralow ballistic to diffusive transition length (4.5-7.6 nm) was observed in GNTs, which... 

Using multiple antennas at the transmit and receive sides of a passive radar brings both the benefits of MIMO radar and passive radar. However one of the obstacles arisen in such configuration is the receive antennas placement in proper positions so that the radar performance is improved. Here we just consider the case of positioning one receiver among multiple illuminators of opportunity. Indeed it is a start for the solution of optimizing the geometry of the multiple receivers in a passive radar