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.

CONTACT angle has an important effect on the dynamic behavior of a droplet during its impact onto a solid surface; this behavior includes deformation, spreading and even rebounding of the droplet from the surface. In this paper, the effect of CONTACT angle during droplet impact is studied and numerically simulated. First, using molecular-kinetic theory and based on the newly available research in this field, a correlation for determining the dynamic CONTACT angle during droplet impact is obtained. This correlation is then implemented in the numerical model used to simulate the process. The results of the numerical model are compared with those of the experiments and those of the previous models (using an equilibrium CONTACT angle; two advancing and receding CONTACT angles). Model predictions agreed well with experimental measurements; this validated the model results for the droplet deformation during the impact. The results show that using the molecular-kinetic theory in modeling CONTACT angle prevents the spreading-and-recoiling oscillations of the droplet that are seen when an equilibrium CONTACT angle is used. Compared to the model with advancing and receding CONTACT angles, the molecular-kinetic theory results in a better prediction of the time and value of the maximum and minimum spread of the droplet on the solid surface. Based on the results of the developed model, a critical maximum spread and two regions of droplet spreading or rebounding from the surface are defined. Next in the paper, an analytical model is presented to study the effect of CONTACT angle on the droplet maximum spread. The results of this model show that for low Capillary numbers (Ca) with an increase of the equilibrium CONTACT angle or a decrease of We number, the maximum spread of the droplet is decreased and becomes less dependent on Re number. In contrast, the maximum spread for high We numbers or low equilibrium CONTACT angles is increased and becomes more dependent on Re number.

Assessment of probability of risk occurrence to the railway system is so important because of severe cost which could be imposed to both railway administration and passengers. Wheel movement on rail is one of the factors which has significant role in overall damage of railway infrastructure. Theses interaction-based defects are divided into several categories such as wheel flat and RCF faults. Nowadays, railway administrations are interested in increasing speed and axle load of rail vehicles due to its economical advantages. Therefore, studies on wheel-rail interaction defect-base become a concern for researchers. Implementing finite element method is a major approach in determining fracture behavior of both wheel and rail. In previous studies, simulations were mainly carried out in 2D domain by considering symmetrical assumptions. The main aim of this paper is to implement FE method based on three dimensional situations with more realistic conditions to assess rail surface crack behavior which is exposed to dynamic moving load. For this purpose, stress intensity factors for different depth of crack was obtained and compared also. The results showed that by increasing crack depth and crack tip position from rail surface, the crack tip stresses and consequently stress intensity factors were decreased.

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.