We present XMM-Newton and Chandra X-ray observations of the middle-aged radio pulsar PSR B0355+54. Our X-ray observations reveal emission not only from the pulsar itself, but also from a compact diffuse component extending ∼ 50 in the opposite direction to the pulsar’s proper motion. There is also evidence for the presence of fainter diffuse emission extending ∼ 5 from the point source. The com...

The study of very large graphs is becoming increasingly prominent in modern-day mathematics. In this paper we develop a rigorous foundation for studying the space of finite labelled graphs and their limits. These limiting objects are naturally countable graphs, and the completed graph space G (V ) is identified with the 2-adic integers as well as the Cantor set. The goal of this paper is to dev...

Tropicalization takes a curve in a hypersurface in 3-space to a balanced rational weighted graph in a tropical surface. In this paper, we study the ‘lifting’ problem: given a graph in a tropical surface, can one find a corresponding algebraic curve in a hypersurface? We develop specific combinatorial obstructions to a graph lifting by studying the factorizations of polynomials with particular N...

In this paper we survey results on packings of congruent spheres in 3-dimensional spaces of constant curvature. The topics discussed are as follows: Hadwiger numbers of convex bodies and kissing numbers of spheres; Touching numbers of convex bodies; Newton numbers of convex bodies; One-sided Hadwiger and kissing numbers; Contact graphs of finite packings and the combinatorial Kepler problem; Is...

A matching queue is described via a graph, an arrival process and a matching policy. Specifically, to each node in the graph there is a corresponding arrival process of items, which can either be queued or matched with queued items in neighboring nodes. The matching policy specifies how items are matched whenever more than one matching is possible. Given the matching graph and the matching poli...

We present a second order numerical scheme to compute capillary bridges between arbitrary solids by minimizing the total energy of all interfaces. From theoretical point view, this approach can be interpreted as computation generalized minimal surfaces using Newton-scheme utilizing shape Hessian. In particular, we give an explicit representation Hessian for functionals on shells involving norma...

This paper discusses, through a review of the main methodologies, representation static var compensators (SVCs) in power flow problem. One consisting full Newton formulation problem, considers thyristor’s firing angle as state variable. The other methodology, also formulation, proposes model which SVC is represented considering reactive injected into bus Furthermore, an improvement to methodolo...

The paper deals with the multilevel solution of elliptic partial differential equations (PDEs) in a finite element setting: uniform ellipticity of the PDE then goes with strict monotonicity of the derivative of a nonlinear convex functional. A Newton multigrid method is advocated, wherein linear residuals are evaluated within the multigrid method for the computation of the Newton corrections. T...

The smoothness-constrained least-squares method is widely used for two-dimensional (2D) and three-dimensional (3D) inversion of apparent resistivity data sets. The Gauss–Newton method that recalculates the Jacobian matrix of partial derivatives for all iterations is commonly used to solve the least-squares equation. The quasi-Newton method has also been used to reduce the computer time. In this...