Different types of Contact, including Contact between node pairs, any-Contact of nodes, and Contacts of the entire network, are used to characterize social relations in mobile social networks. Different modes of routing, from the point of view of message delivery semantics, encompass unicasting, multicasting, any-casting, and broadcasting. Studies have shown that using probability distribution functions of Contact data, which is mainly assumed to be homogeneous for nodes, improves the performance of these networks. However, there exists an important challenge in studies on distributions. A lot of works apply the distribution of one type of Contact to other types. Hence in routing applications, it causes to use of the distribution of one type of Contact for any mode of routing. This study provides a complete solution to model each type of homogeneous Contact data distribution and to use them in different modes of routing. We propose a routing algorithm that uses this new model. Results show that our solution improves the average latency of comparing methods Epidemic, TCCB, and DR about 3.5-times, 30%, and 45%, respectively. It achieves a delivery rate of about 5% and 6%, and average latency about 6% and 8% better than that of DR and TCCB, respectively.

The neoclassical growth model is tested by use of panel data procedure in this research. In the econometric test, simoultanously time series and cross detection will be compared on the basis of panel data method through which their observed points increase and consequently the estimation efficiency will be increased. The examination of neoclassical growth theory has been done with reference to external & internal factors of 52 selected countries from 1960 to 2000. The independent variable of model has been selected on the basis of the result of previous research which explains the result in three separate models: developed countries, developing countries, and whole countries. These factors are such as: Gross National Products with lag of period, work force age, growth rate, education level, the change of capital accumulation and economic trade volum. The consequences of this research is that: neoclassical growth model can explain the major part of economic growth of the countries with use of internal variables. Also with the use of panel procedure of fixed effect, we can see the fundamental differences and structure of the growth process for different countries; and show how the economic, and social conditions affect on the growth.

Subsequent to rails, sleepers are the most important elements of the railway superstructures, for which its role is to keep the geometry of the line, resist against vertical and lateral loads and transfer them to the layer of ballast. Contact point between sleeper and ballast play an important role in defecting of the railway tracks. For this reason; method of analysis, design and built of sleepers and also how they have been implemented in superstructures are of an important issue in the railway engineering researches. This paper presents investigation of Contact stress distribution in lower surface of sleepers through some experiments on railway tracks. In this experiment one sleeper equipped with several load cells was installed on a railway track situated in Bahram station. After tamping, some load was passed over the sleeper and the exerted forces were measured and consequently were analyzed as an output. It should be stressed that passing trains with an identified axial load were passed over the installed sleeper before and after the stabilization. Results show the real Contact stress distribution in lower surface of the sleeper in different status i.e. (after tamping, before and after stabilizing) and the effect and importance of required ballast compaction under the sleepers. With due consideration to the results achieved, it could be said that; right amount of ballast, sufficient compaction under the sleeper and performance of railway track's repair and maintenance machineries are of utmost importance and reduces non-uniformity of load distribution.

One of the parameters that play an important role in the efficiency of polymer electrolyte membrane fuel cells (PEMFCs) is the Contact pressure between the bipolar plates and membrane electrode assembly (MEA). Increasing or decreasing the Contact pressure between the plates causes ohmic losses and decreases the efficiency of the fuel cell. In this research, the Contact pressure distribution over the MEA in the three-cell fuel cell stack with metallic bipolar plates with an active area of 100 cm2 was investigated numerically and experimentally. Abaqus finite element software has been used for finite element simulation. Due to the asymmetry of the flow field of metallic bipolar plates, a full three-dimensional model has been used for simulation. In order to experimentally investigate the Contact pressure distribution on the MEA, the pressure sensitive film of Fujifilm was used. Considering that the fuel cell stack includes three cells, pressure sensitive film is used in the middle cell and thin insulating plates are used in the first and third cells. Finally, after disassembling the fuel cell stack and separating the pressure sensitive film, the experimental test results are compared with the simulation results. The simulation results showed that the pressure changes on the active area are less than 0.3 MPa. The average Contact pressure on the active area with a press force of 3.7 tons is about 1 MPa. Also, the results of the experimental tests were in good agreement with the simulation results.

One of the obvious reasons for most disorders in network service provisioning is network path congestion. Congestion avoidance in today's networks is too costly and sometimes impossible. With the introduction of SDN, centralizing the equipment's control plane has become possible. This paper presents an enhanced method named ESV-DBRA to avoid congestion in multi-tenant SDN networks. At first, ESV-DBRA monitors the traffic load and delay of all network paths for each tenant individually. Then, by merging the parameters obtained from the monitoring, the Service Level Agreements (SLA), and a novel proposed cost function, it calculates the cost of the network paths per tenant. As a result, traffic for each tenant is routed through the path/paths at the lowest possible cost from the tenant's perspective. Next, the bandwidth quotas will be calculated and assigned to the tenants over their optimal routes. Afterward, whenever congestion is likely to occur in a path, ESV-DBRA automatically changes the route or bandwidth of the tenants' traffic related to this path to avoid congestion. Related algorithms are also proposed.Eventually, simulations show that the proposed method effectively increases bandwidth utilization by 10.76%.

Todays gamma knife radiosurgery is used widely for treatment of very small brain tumors. In order to investigate accuracy of dosimetry and treatment planning calculations, using Monte Carlo simulation with dedicated code named as beamnrc including non-CT data and CT data options is necessary. The aim of this study is choosing the best options in order to have an accurate tools based on their advantages and disadvantages. In this study, gamma knife unit 4C along with standard water equivalent phantom and EBT3 films were used to obtain dose distributions. Monte Carlo simulation was done with non-CT data and CT data options of the code and their resulting dose were compared. Comparison the calculated and measured dose distributions at X, Y and Z axis showed gamma value below 1 which verified Monte Carlo simulations. Also comparing the dose distributions from both non-CT data and CT data with each other implies that there is no significant difference between two methods. Based on the obtained results using non-CT data and CT data results in the same dose distribution. So for simplicity, using non CT data for regular phantom shapes is preferred.