Structure diagram and dynamics of formation of hexagonal boron nitride in phase-field crystal model

The phase-field crystal (PFC-model) is a powerful tool for modelling of the crystallization in colloidal and metallic systems. In the present work, the modified hyperbolic phase-field crystal model for binary systems is presented. This model takes into account slow and fast dynamics of moving interfaces for both concentration and relative atomic number density (which were taken as order parameters). The model also includes specific mobilities for each dynamical field and correlated noise terms. The dynamics of chemical segregation with origination of mixed pseudo-hexagonal binary phase (the so-called ‘triangle phase’) is used as a benchmark in two spatial dimensions for the developing model. Using the free energy functional and specific lattice vectors for hexagonal crystal, the structure diagram of co-existence of liquid and three-dimensional hexagonal phase for the binary PFC-model was carried out. Parameters of the crystal lattice correspond to the hexagonal boron nitride (BN) crystal, the values of which have been taken from the literature. The paper shows the qualitative agreement between the developed structure diagram of the PFC model and the previously known equilibrium diagram for BN constructed using thermodynamic functions. This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’.

PEMODELAN APLIKASI BOOKING TIKET MENGGUNAKAN UNIFIED MODELING LANGUAGE

Pengembangan sebuah aplikasi merupakan inovasi untuk menyelesaikan masalah. Untuk melakukan pengembangan aplikasi terdapat berbagai teknik pengembangan. pengembangan aplikasi berbasis web dan pengembangan aplikasi berbasis mobile memiliki perlakuan yang berbeda. Namun yang paling penting dari proses pengembangan aplikasi adalah pemodelan informasi aplikasi itu sendiri. karena dengan adanya pemodelan proses pengembangan akan lebih terarah dan sistematis. Pemodelan memiliki kemapuan menggambarkan cetak biru dari aplikasi yang akan dikembangkan. Untuk itu pada penelitian ini akan dilakukan pemodelan aplikasi menggunakan unified modeling language. Pemodelan dilakukan guna mempermudah proses pengembangan dengan kasus aplikasi booking tiket. Penggunaan unified modeling language dalam melakukan pemodelan juga disebabkan notasi unified modeling language memiliki kemampuan dalam menggambarkan berbagai proses dalam sebuah aplikasi yang dikembangkan. Hasil dari penelitian ini berupa pemodelan aplikasi dengan unified modeling language yang digambarkan dalam tiga bentuk notasi yaitu structure diagram yang digambarkan dalam bentuk class diagram, communication diagram yang digambarkan dalam bentuk activity diagram dan behavior diagram yang digambarkan dalam bentuk use case diagram. Pemodelan aplikasi juga diimplementasikan dalam bentuk prototype aplikasi dengan fitur pemesanan tiket, proses konfirmasi, jadwal keberangkatan serta pengelolaan data terkait dengan proses pemesanan tiket. The development of an application is an innovation to solve problems. To develop applications, there are various development techniques. Web-based application development and mobile-based application development have different treatments. However, the most important part of the application development process is modeling the application information itself. because with the modeling the development process will be more directed and systematic. Modeling can describe the blueprint of the application to be developed. For this reason, this research will conduct application modeling using the unified modeling language. Modeling is done in order to simplify the development process with the ticket booking application case. The use of unified modeling language in modeling is also due to the notation that unified modeling language can describe various processes in a developed application. The results of this study are in the form of application modeling with a unified modeling language which is depicted in three notation forms, namely a structure diagram depicted in the form of a class diagram, a communication diagram depicted in the form of an activity diagram and a behavior diagram depicted in the form of a use case diagram. Application modeling is also implemented in the form of application prototypes with ticket booking features, confirmation processes, departure schedules and data management related to the ticket booking process

Feedback-Dubins-RRT Recovery Path Planning of UUV in an Underwater Obstacle Environment

In this paper, a UUV (Unmanned Underwater Vehicle) recovery path planning method of a known starting vector and end vector is studied. The local structure diagram is designed depending on the distance and orientation information about the obstacles. According to the local structure diagram, a Rapidly exploring Random Tree (RRT) method with feedback is used to generate a 3D Dubins path that approaches the target area gradually, and the environmental characteristic of UUV reaching a specific target area is discussed. The simulation results demonstrate that this method can effectively reduce the calculation time and the amount of data storage required for planning. Meanwhile, the smooth spatial path generated can be used further to improve the feasibility of the practical application of UUV.

Variability of rock pressure along the length of the working face

Introduction. Common deepening of mining causes problems with maintaining the achieved production capacity. The ability of the mechanized supports to withstand rock pressure in such conditions is questioned. Modern supports equipped with pressure sensors will make it possible to control and prevent the negative impact of the increased rock pressure and visualize the results. Research aim is to determine the rock pressure variation rate along the length of the longwall in order to avoid its negative impact and to plan the capacity of the cutter-loader and load upon the working face in various mining and geological conditions in a more substantiated way. Methodology. The use of the Surfer software to visualize the processes of displacement and construct the geomechanical structure diagram of the coal-bearing disintegrated rock mass in the form of geomechanical layers hierarchy makes it possible to forecast the sites with the increased rock pressure upon the coal bed and the longwall support. Results. Timely and well-grounded determination of the sites with the increased rock pressure upon the coal bed and the powered support at the longwall face advance is the technical results of the research. Analysis and discussion. The geomechanical structure diagram shows the sequence of disintegrated rock displacement arches development. Overburden and bearing pressure acts upon the coal bed between the displacement arches and depends on the depth of coal bed occurrence, working face advance speed and the strength of the roof rock. It is the sum of the overburden and bearing pressure that is reflected on the state of the coal bed ahead of the face of the longwall; their impact is wave-like. Summary. The diagram will make it possible to forecast the sites subject to the negative impact of rock pressure along to length of the longwall and improve the effectiveness of coal bed mining by means of more accurate calculation of load upon the working face and the capacity of the cutter-loader, specify the force of cutting machine working elements during coal bed breaking, choose the support of the longwall according to the load-carrying capability, plan some measures to eliminate the negative impact of rock pressure at particular sites, and strengthen the marginal part of the bed in order to reduce visible coal sloughing.