241 research outputs found
The multiplicative version of the edge Wiener index
No full textThe multiplicative Wiener index π, which was introduced by Ivan Gutman et al. in [5], is a molecular structure descriptor equal to the product of the distances between all pairs of vertices of the underlying molecular graph G. Also, Iranmanesh et al. in [7], introduced the edge-Wiener index of a graph. It obtains in term of the distances between all pairs of edges set of a graph. We define a new index called the multiplicative edge-Wiener index that is equal to product of distance between all pairs of edges set of a graph G. Moreover, we compute this index for some well- known graphs and we consider its relation to the edge-Wiener index in alkanes, as well
An additive model for spatio-temporal smoothing of cancer mortality rates
No full textIn this paper, a Bayesian hierarchical model is used to anaylze the female breast cancer mortality rates for the State of Missouri from 1969 through 2001. The logit transformations of the mortality rates are assumed to be linear over the time with additive spatial and age effects as intercepts and slopes. Objective priors of the hierarchical model are explored. The Bayesian estimates are quite robustness in terms change of the hyperparamaters. The spatial correlations are appeared in both intercepts and slopes
A Survey on CubeSat Missions and Their Antenna Designs
No full textCubeSats are a class of miniaturized satellites that have become increasingly popular in academia and among hobbyists due to their short development time and low fabrication cost. Their compact size, lightweight characteristics, and ability to form a swarm enables them to communicate directly with one another to inspire new ideas on space exploration, space-based measurements, and implementation of the latest technology. CubeSat missions require specific antenna designs in order to achieve optimal performance and ensure mission success. Over the past two decades, a plethora of antenna designs have been proposed and implemented on CubeSat missions. Several challenges arise when designing CubeSat antennas such as gain, polarization, frequency selection, pointing accuracy, coverage, and deployment mechanisms. While these challenges are strongly related to the restrictions posed by the CubeSat standards, recently, researchers have turned their attention from the reliable and proven whip antenna to more sophisticated antenna designs such as antenna arrays to allow for higher gain and reconfigurable and steerable radiation patterns. This paper provides a comprehensive survey of the antennas used in 120 CubeSat missions from 2003 to 2022 as well as a collection of single-element antennas and antenna arrays that have been proposed in the literature. In addition, we propose a pictorial representation of how to select an antenna for different types of CubeSat missions. To this end, this paper aims is to serve both as an introductory guide on CubeSats antennas for CubeSat enthusiasts and a state of the art for CubeSat designers in this ever-growing field
THE STRUCTURE OF UNIT GRUOP OF
No full textLet be the gruop ring of the group over ring and be its unitgroup. In this paper, we obtain the structure of unit group of
A characterization of the linear groups
No full textsummary:Let be a finite group and be the set of element orders of . Let and be the number of elements of order in . Set . In fact is the set of sizes of elements with the same order in . In this paper, by and order, we give a new characterization of finite projective special linear groups over a field with elements, where is prime. We prove the following theorem: If is a group such that and consists of , , and some numbers divisible by , where is a prime greater than with modulo , then
On bipartite divisor graph for character degrees
No full textThe concept of the bipartite divisor graph for integer subsets has been considered in [M. A. Iranmanesh and C. E. Praeger, Bipartite divisor graphs for integer subsets, Graphs Combin., 26 (2010) 95--105.]. In this paper, we will consider this graph for the set of character degrees of a finite group and obtain some properties of this graph. We show that if is a solvable group, then the number of connected components of this graph is at most and if is a non-solvable group, then it has at most connected components. We also show that the diameter of a connected bipartite divisor graph is bounded by and obtain some properties of groups whose graphs are complete bipartite graphs
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