Sharif Digital Repository

A capacitive voltage transformer (CVT) operating at extra high voltage (EHV) is examined for measuring power system harmonics in this paper. With the capacitor connections rearranged in the divider, the internal components can be energized with their nominal values by applying an intermediate voltage. Through this procedure, the effect of different burdens on frequency response is tested. The linearity of CVT circuits is also evaluated with respect to applied voltage level. In addition, an examination of the effects of amplitude and phase differences between harmonic components and the fundamental component is conducted. The practical test results are subsequently discussed. © 2022 IEEE  

In this paper, dynamic resource allocation and multicast routing algorithms are proposed for elastic optical networks (EONs). The proposed algorithms find the shortest path trees by modeling either the amount of free spectrum in each link or the link length as the cost function of routing method. The proposed algorithms are simulated in the dynamic operation scenario over the so called US Backbone topology. Simulation results reveal that by considering the cost function of routing algorithm based on the available spectrum in each link will improve the blocking probability while reduce the spectrum efficiency. On the other hand, by considering link length as the cost function, the blocking... 

In this paper, we formulate an integer linear programming (ILP) to perform multicast routing and spectrum assignment (MRSA) in elastic optical networks, which serves jointly a set of multicast requests. In this formulation, all physical layer restrictions including modulation level assignment, maximum number of multicast capable nodes (MCNs), and maximum splitting degree (MSD) of MCNs, are considered. In addition, we modify the proposed joint ILP to serve multicast requests one-by-one, which is referred to as a separate ILP. Furthermore, we present three heuristic algorithms for MRSA, namely distance-based MRSA (DMRSA), congestion-based MRSA (CMRSA), and mixed CMRSA/DMRSA, which are... 

Embedding metrics into constant-dimensional geometric spaces, such as the Euclidean plane, is relatively poorly understood. Motivated by applications in visualization, ad-hoc networks, and molecular reconstruction, we consider the natural problem of embedding shortest-path metrics of unweighted planar graphs (planar graph metrics) into the Euclidean plane. It is known that, in the special case of shortest-path metrics of trees, embedding into the plane requires Θ(√n) distortion in the worst case [M1], [BMMV], and surprisingly, this worst-case upper bound provides the best known approximation algorithm for minimizing distortion. We answer an open question posed in this work and highlighted by... 

In this study, the authors explore a generalised scheme for the synchronous code division multiple access (CDMA). In this scheme, unlike the standard CDMA systems, each user has different codewords for communicating different messages. Two main problems are investigated. The first problem concerns whether uniquely detectable overloaded matrices (an injective matrix, i.e. the inputs and outputs are in one-to-one correspondence depending on the input alphabets) exist in the absence of additive noise, and if so, whether there are any practical optimum detectors for such input codewords. The second problem is about finding tight bounds for the sum channel capacity. In response to the first... 

Embedding metrics into constant-dimensional geometric spaces, such as the Euclidean plane, is relatively poorly understood. Motivated by applications in visualization, ad-hoc networks, and molecular reconstruction, we consider the natural problem of embedding shortest-path metrics of unweighted planar graphs (planar graph metrics) into the Euclidean plane. It is known that, in the special case of shortest-path metrics of trees, embedding into the plane requires Θ(√n) distortion in the worst case [19, 1], and surprisingly, this worst-case upper bound provides the best known approximation algorithm for minimizing distortion. We answer an open question posed in this work and highlighted by... 

In this study the authors present an in-depth study, analysis and discussion on maximum likelihood (ML)-based receiver for a typical spectrally encoded spread-time CDMA in the presence of multiple narrowband interference (NBI) signals in an additive white Gaussian noise channel. Furthermore, the authors demonstrate that by combining useful properties of ML-based receiver and three-level codes, that is, codes with values of -1, 0, +1, the authors can introduce a new strategy in which superior performance with respect to previous receiver structure based on two-level codes, that is, codes with values of -1, +1, can be attained. With the help of an example, the authors drive, first, the... 

In this study, we discuss the postural stability of a nonprehensile manipulation problem, which deals with multibody objects. As a metric for postural stability, we define PRI. Then, the system is posturally stable, if PRI is inside the convex hull of the object-manipulator contact surface. We then discuss that dynamic biped locomotion is a special case of dynamic nonprehensile manipulation in all aspects; we prove that ZMP (zero-moment point) and FRI (zoot rotation indicator) are special cases of PRI (palm rotation indicator). Simulations and experiments corresponding to simple examples support the results