Contents:

  • Isyna Muna and Szymon Winczewski Molecular Dynamics Simulations of Thermal Conductivity of Penta-Graphene   abstract | full text
  • Henryk Krawczyk and Andrzej Sobecki Smart Shop Services for Building Customer-Oriented Scenarios   abstract | full text
  • Leonardo Pasini and Nicola Del Giudice Simulation of a vehicular traffic system based on queueing network models: comparative analysis of two models   abstract | full text

Abstracts:

hIsyna Muna and Szymon Winczewski Molecular Dynamics Simulations of Thermal Conductivity of Penta-Graphene

Abstract: The thermal conductivity of penta-graphene (PG), a new two dimensional carbon allotrope and its dependence on temperature, strain, and direction are studied in this paper. The thermal conductivity of PG is investigated using a non-equilibrium molecular dynamics simulation (NEMD) with the Two Region Method by applying the optimized Tersoff interatomic potential. Our study shows that the thermal conductivity of PG (determined for the [100] direction) at the room temperature of 300 K is about 18.7 W/(m K), which is much lower than the thermal conductivity of graphene. As the temperature increases, the thermal conductivity of PG is decreasing because, unlike graphene, PG has lower phonon group velocities and few collective phonon excitations. The obtained dependence of the thermal conductivity on the temperature can be described as κ ∼ T −0.32. For the [110] direction the thermal conductivity at the room temperature of 300 K is very similar: about 17.8 W/(m K). In this case, the temperature dependence follows the κ ∼ T −0.3 relation. Our investigations reveal that the thermal conductivity of PG is isotropic, meaning that heat transport behavior is independent of the heat flow direction. Our results indicate that the thermal conductivity of PG depends in an interesting way on the applied strain: nonmonotonic up-and-down behavior is observed. The thermal conductivity increases between strains from 0% up to 12.5%, and it decreases above a strain of 12.5%. Our investigation highlights the fascinating thermal transport properties of penta-graphene. The ultra-low thermal conductivity, the decreasing thermal conductivity with the increasing temperature, and the ultra-high mechanical strength of PG show that PG possesses a great potential in thermoelectric and nanomechanics applications. We hope that these findings, made by means of simulations, will become a bridge to inspire and encourage the experimental works, especially in the synthesis of PG.

 

hHenryk Krawczyk and Andrzej Sobecki Smart Shop Services for Building Customer-Oriented Scenarios

Abstract: The shops of today mostly support the customer by offering him or her products based on basic relationships between products viewed or ordered by users with similar tastes. This common approach may fail in many cases especially when the user does not have sufficient knowledge about the market, or when he or she wants to build a set of products in more than one shop. New categories of smart shop services are proposed in order to execute such customer-oriented scenarios where recommended products do meet mutual dependencies with products previously ordered by the customer. An attempt is made to collect additional information about the behavior of users (from past and current contexts) and represent it in a targeted graph called the customer-oriented scenario. Four types of such scenarios are distinguished depending on how many shops have been visited by the user before buying the expected products and how many products the user wants to buy. Moreover, the proposed scenario model provides the possibility of showing which services had been used by the user before the selection was made. Customer-oriented scenarios may be created post factum based on event data logs or before the user will use the shop, which means that it can be arranged which information, knowledge sources (internal or external), products or categories should be suggested in some context of the user's decision. The possibility of leveraging additional smart services into a traditional trading platform may help users, especially when they want to implement a complex scenario and order many products with mutual dependencies or in a situation when the user wants to understand the market before buying something. Using internal and external services allows creating a network for distributing knowledge focused on the actual customer context in a shop.

 

hLeonardo Pasini and Nicola Del Giudice Simulation of a vehicular traffic system based on queueing network models: comparative analysis of two models

Abstract: In the previous works we presented a study for modeling and simulation of vehicular traffic systems based on queuing networks. Specifically, in paper (Pasini and Bianchini, 2019), we studied the urban network located in North Siena, in the city of Siena (Italy), in its actual layout, after the Municipality had introduced some changes for vehicular flow management. This system is based on two roundabouts and a crossroad, as shown in Figure 1. In this work, we are going to conclude our previous study, comparing the actual vehicular flow and the flow derived from an alternative system, foreseen by the PRG of the Municipality of Siena which is composed of three roundabouts and which has not been implemented yet.

 

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