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Nowadays, nearly all things sold worldwide are transported through sea using ships. It's mean that maritime has a big role impact on human life in the world. However, the increase of maritime mobilities comes also with various issues from transshipment, oil spilling, until hijacking. Initially, a device such as Automatic Identification System (AIS) has been widely deployed and used to provide a cooperative position report for marine communication but nowadays it is also deployed to overcome the issues. In recent work, AIS is also installed on the satellite as space-based AIS to get worldwide coverage. The data have shown that falsification of AIS messages is possible, and therefore could mask or favor illegal actions, lead to disturbance of monitoring systems and new maritime risks. This paper presents these new threats and introduces a novel algorithm for detecting spoofing. The algorithm is quite straight forward by comparing vessel displacement and distance. Some variances are introduced to produce the best algorithm. The area of interest for this research is Indonesia with longitude from 95° to 141° and latitude -11° to 6°. AIS data from LAPAN-A2 and LAPAN-A3 satellites are used with ranged from January 1, 2019 until June 30, 2019. From this research, the best algorithm was achieved by using an average speed with constant tolerance of 61.596 km. [ABSTRACT FROM AUTHOR]

To fulfill its operational function, the Sun-synchronous satellite needs to have a specific nodal precession value of 360°/year. This nodal precession value is mainly affected by semi-major axis, eccentricity, and inclination. However, in fact, semi-major axis and inclination of an orbit often drift over a long period of operation. Thus, the nodal precession of the orbit will be no longer 360°/year. This paper discusses the simulation of inclination maneuver to correct the nodal precession of Sun-synchronous satellite by using a non-impulsive thruster approach. Data from LAPAN Sun-synchronous satellite was used for simulation. The results of the simulation show that there are no significant changes to other orbital parameters for inclination maneuver for every 1, 2, 3, 4, and 6 months. Also, the results of the simulation are compared to the analytical results (impulsive thruster approach), which turns out that the analytical approach still gives a good accuracy of inclination changes for that maneuver interval with accuracy up to 0.001°. The results can be used as a recommendation for the thruster operation of the next LAPAN Sun-synchronous satellite. [ABSTRACT FROM AUTHOR]

In this paper, we derived the explicit formula of Chebyshev polynomials of the third kind and the fourth kind by using a composita FΔ(n,k) of a generating function F(t) = ∑n>0fn tn . By multiplying (1 - t) to the composition of generating function, G(t) = 1/1-t and F(x,t) = 2xt - t², that has a composita FΔ(n,k), the coefficients of chebysshev polynomials of the third kind can be found. Moreover, by multiplying (1 + t) to the composition of generating functions G(t) = 1/1-t and F(x,t) = 2xt - t², that has a composita FΔ (n,k), the coefficients of chebyshev polynomials of the fourth kind can be obtained. From those coefficients, the explicit formula of chebyshev polynomials of the third and the fourth kinds are derived. [ABSTRACT FROM AUTHOR]

An adjacency matrix A(G) of directed graph G is an m×m matrix consisting of only entries 0 and 1, where m is the number of vertices of G. The entry aij is equal to 1 if there exists a directed edge from vertex vi to vertex vj, otherwise it is equal to 0. Let D(G) be a diagonal matrix of size m×m with each of its main diagonal entry being the degree of the corresponding vertex of directed graph G. Then the matrix L(G) = D(G) − A(G) is called the Laplacian matrix of G. Since a directed graph has two types of degrees namely indegree and outdegree, they result in directed graphs also having the both types of its Laplacian matrices. In this study, the adjacency matrix and the Laplacian matrix of cyclic directed prism graph are investigated. The general form of the coefficients of polynomial characteristic of the Adjacency matrix and Laplacian matrix, respectively is obtained by applying the row reduction method in linear algebra, whereas the general form of the eigenvalues of the polynomial characteristic of the Adjacency matrix and Laplacian matrix, respectively is obtained by factorization and substitution methods. [ABSTRACT FROM AUTHOR]

A prism graph is a graph which corresponds to the skeleton of an n-prism and therefore it is a cyclic simple graph. It is denoted Yn (n ≥ 3) where n is half the number of vertices. An n-prism graph has 2n vertices and 3n edges. In this paper, only regularly-directed cyclic prism graphs are investigated. The anti-adjacency matrix is applied as the graph representation. An anti-adjacency matrix of graph representation is a 0–1 matrix of size m × m where m is the number of vertices. The entry bij of an anti-adjacency matrix B(G) of directed graph G is 0 if there exists a directed edge from vertex vi to vertex vj and is 1 otherwise. The characteristic polynomial of the anti-adjacency matrix B(Yn) of directed cyclic prism graph Yn are obtained. The characteristic polynomial will be proved by observing the both cyclic and acyclic induced subgraphs of the directed cyclic prims graph. Furthermore, the anti-adjacency matrix of directed cyclic prism graph is found to have both real eigenvalues and complex eigenvalues which appear in conjugate pairs. [ABSTRACT FROM AUTHOR]

In graph theory, the robustness of a network measures its resilience (in terms of connectivity) to either removal of network nodes or edges. Using algebraic connectivity is one of the best way to measure the robustness of a network. The higher algebraic connectivity means more robust network. The goal of this work is to improve the robustness of an existing air transportation network. It can be accomplished by adding edges (routes) to the network. However, due to limited budget and aircraft, the routes to be added have to be chosen carefully. The best routes to be added are the routes that will yield the highest algebraic connectivity when they were added to the network. This problem of choosing the best routes to be added is called flight routes addition. In this paper, the flight routes addition is solved using Tabu Search method with the algebraic connectivity component to choose two new lines to strengthening the robustness of the flight routes. We only consider the robustness and do not. [ABSTRACT FROM AUTHOR]