77 research outputs found
Nearest Neighbor Connectivity in Two-Dimensional Multihop MANETs
A Mobile Ad Hoc Network (MANET) is characterized to be a network with free, cooperative, and dynamic nodes, self-organized in a random topology, without any kind of infrastructure, where the communication between two nodes usually occurs using multihop paths. The number of hops used in the multihop path is an important metric for the design and performance analysis of routing protocols in MANETs. In this paper, we derive the probability distribution of the hop count of a multihop path between a source node and a destination node, fixed at a known distance from each other, and when a fixed number of nodes are uniformly distributed in a region of interest. This distribution is obtained by the Poisson randomization method. To obtain the multihop path, we propose a novel routing model in which the nearest distance routing protocol (NR) is analyzed. Numerical results are obtained to evaluate the performance of the NR
A Possibility of Detecting Fast Neutrons in a 10B Solid-gas Detector
The possibility of detecting thermal and fast neutrons in 10B solid-gas detector is considered. The simulation of the neutron detection process shows a significant difference in the detector signals caused by neutrons of different energies. An experimental verification of the detector’s operation was performed using W-Be photoneutron source with different ratio of fast and thermal neutrons incident on the detector. The measured amplitude spectra of the signals for different neutron energies were compared with the simulation results. The qualitative agreement between experimental and calculated data indicates the possibility of using this detector for recording thermal and fast neutrons
Cell shape analysis of random tessellations based on Minkowski tensors
To which degree are shape indices of individual cells of a tessellation
characteristic for the stochastic process that generates them? Within the
context of stochastic geometry and the physics of disordered materials, this
corresponds to the question of relationships between different stochastic
models. In the context of image analysis of synthetic and biological materials,
this question is central to the problem of inferring information about
formation processes from spatial measurements of resulting random structures.
We address this question by a theory-based simulation study of shape indices
derived from Minkowski tensors for a variety of tessellation models. We focus
on the relationship between two indices: an isoperimetric ratio of the
empirical averages of cell volume and area and the cell elongation quantified
by eigenvalue ratios of interfacial Minkowski tensors. Simulation data for
these quantities, as well as for distributions thereof and for correlations of
cell shape and volume, are presented for Voronoi mosaics of the Poisson point
process, determinantal and permanental point processes, and Gibbs hard-core and
random sequential absorption processes as well as for Laguerre tessellations of
polydisperse spheres and STIT- and Poisson hyperplane tessellations. These data
are complemented by mechanically stable crystalline sphere and disordered
ellipsoid packings and area-minimising foam models. We find that shape indices
of individual cells are not sufficient to unambiguously identify the generating
process even amongst this limited set of processes. However, we identify
significant differences of the shape indices between many of these tessellation
models. Given a realization of a tessellation, these shape indices can narrow
the choice of possible generating processes, providing a powerful tool which
can be further strengthened by density-resolved volume-shape correlations.Comment: Chapter of the forthcoming book "Tensor Valuations and their
Applications in Stochastic Geometry and Imaging" in Lecture Notes in
Mathematics edited by Markus Kiderlen and Eva B. Vedel Jense
Structure and Electric Conductivity of Zirconate Barium Yttrium-Doped
This work is devoted to the study of the structural and electrical transport properties of yttrium-doped barium zirconate. The activation energies of partial conductivities were calculated at different temperature values in a wide range of partial pressure of water vapor and oxygen.Работа была выполнена при поддержке гранта РНФ №18-73-00022
DETERMINATION OF THE CHEMICAL DIFFUSION COEFFICIENT AND THE CONSTANT OF SURFACE OXYGEN EXCHANGE GdBaCo2-xFexO6-δ
This work is devoted to the determination of diffusion coefficients and constants of surface oxygen exchange in double perovskites, barium and gadolinium cobaltites by ECR (electrical conductivity relaxation) method. The values of the total electrical conductivity were also determined.Работа была выполнена при поддержке Министерства Науки и Высшего Образования РФ, соглашение № 075-03-2021-051/5
Steepest descent algorithms in a space of measures
The paper describes descent type algorithms suitable for solving optimisation problems for functionals that depend on measures. We mention several examples of such problems that appear in optimal design, cluster analysis and optimisation of spatial distribution of coverage processes
On search sets of expanding ring search in wireless networks
We focus on the problem of finding the best search set for expanding ring search (ERS) in wireless networks. ERS is widely used to locate randomly selected destinations or information in wireless networks such as wireless sensor networks. In ERS, controlled flooding is employed to search for the destinations in a region limited by a time-to-live (TTL) before the searched region is expanded. The performance of such ERS schemes depends largely on the search set, the set of TTL values that are used sequentially to search for one destination. Using a cost function of searched area size, we identify, through analysis and numerical calculations, the optimum search set for the scenarios where the source is at the center of a circular region and the destination is randomly chosen within the entire network. When the location of the source node and the destination node are both randomly distributed, we provide an almost-optimal search set. This search set guarantees the search cost to be at most 1% higher than the minimum search cost, when the network radius is relatively large
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