This article considers a problem to choose parameters of a procedure for
changing node roles in a multi-gateway wireless ad hoc network used in
aerospace systems. Mathematical formulation of a mixed-integer programming
(MIP) model to optimize the changing-node-role-procedure parameters is
proposed, where the attention is focused on appropriate parameterization in
order to make it possible to include additional constraints, if necessary.
A practical two-stage technique used by the authors to solve the considered
problem is briey discussed. On the first stage, the branch-and-bound
algorithm, provided with cutting plane constraints of some classes, is
applied to choose optimal roles of the network nodes. On the second stage,
the network simulator developed by the authors is used to estimate main
characteristics of the resulting network. Workability of the proposed
approach is demonstrated by results of computational experiments.
To solve the problem of manufacturing fright cars with increased carrying capacity and reliability it is offered to use in their design a center sill with a new type of a cantilever part created on the basis of a cast part of front and back unified stops. Special requirements to the characteristics of a cast part defined a necessity to develop techniques for its manufacturing with the aid of science intensive experiments and current methods of the computer analysis. The work is devoted to the description of methods and technological developments allowing the support of manufacturing a complex and significant cast part. The design of casting technology was carried out with the use of computer simulation. To ensure high wear-resistance of a body center plate there was developed a technology of hardening with high frequency current on the basis of computations and full-scale experiments.
The paper presents the network layer of the protocol stack in wireless sensor networks. This stack makes it possible to implement wireless sensor networks of a tree topology, which are able to function in the presence of noise. We state the requirements for the network layer and propose a development to the keep-alive mechanism that forms the basis of the network recovery subsystem. We present a functional flow block diagram of the network layer proposed and its model based on the ns-3 simulator. We also describe the noise model. Our simulation allowed us to estimate how noise interferes with the network operation and to show that the network layer of the protocol stack for a wireless sensor network featuring a network recovery mechanism is efficient in the presence of noise
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