Abstract

Most of the previously proposed schemes use temporary identities for mobile users to provide unlinkable anonymous authentication for mobile users to the satellite network control center (NCC), where the temporary identities are picked at random after each session and agreed between a mobile user U and the NCC for the next session. Although such schemes provide full anonymity and are computationally efficient, the common problem with such strategies is that an adversary is able to desynchronize the temporary identity shared between U and NCC by means of simple jamming attack at a certain round in the authentication protocol. It results in the denial of all future sessions unless U re‐registers a new identity at the NCC. In this paper, we propose a new authentication scheme for mobile satellite networks. We avoid using synchronized temporary identities, which are always vulnerable to desynchronization attacks. We also avoid multi‐round authentication phase in order to reduce the jamming effect. Instead, a mobile user is able to create a new blinded version of his clear identity for each established session noninteractively, allowing him to anonymously authenticate himself to NCC in a fully unlinkable fashion. Moreover, in few milliseconds and one move non‐interactive way, U is able to establish a session key with NCC in a fully anonymous and authenticated way. Our new scheme uses recent advances in elliptic curve cryptography, and hence, it is efficient for implementation on mobile devices with limited resources. Through the rigorous security analysis using the broadly accepted Burrows–Abadi–Needham logic, informal security analysis, and the simulation for formal security verification using the widely known automated validation of Internet security protocols and sapplications tool, we show that our scheme is secure against various known attacks. Copyright © 2017 John Wiley & Sons, Ltd.

Abstract

The sensitivity of a monolithically integrated semiconductor ring laser gyro is severely limited by the high value of the lock-in threshold. In this work, we calculate the lock-in threshold using perturbation theory and coupled mode theory analysis. It is shown that gyro sensitivity is limited to an input rotation rate of 10^8  deg / h due to nonlinear coupling between the countertraveling modes. This coupling arises due to the backreflection of modes from moving index gratings, induced by rotation. Lock-in threshold is directly proportional to the strength of nonlinear coupling and spatial overlap of the modes’ energy densities with periodic index perturbations.

Abstract

The moving population inversion gratings formed due to spatial hole burning inside a semiconductor ring laser gyroscope causes nonlinear coupling of the counter-traveling modes. We mathematically demonstrate this phenomenon using Perturbation Theory and calculate the limit imposed by it on the sensitivity of inertial rotation.

Abstract

The effects of phase-amplitude interactions on the linearity of semiconductor ring laser gyro output is evaluated. Response of gyro output to the variations in several semiconductor gain medium parameters is studied with a view of performance enhancement through parameter optimization.

Abstract

A novel method of lock-in elimination using electro-optic phase modulator in semiconductor ring laser gyroscope is proposed. It helps in operating the gyro out of the lock-in band, thus improving its sensitivity.

Abstract

Conservative coupling of modes in an integrated external-cavity semiconductor ring laser is used to suppress lock-in in an inertial rotation sensor. Extent of suppression is dependent on refractive index difference between active and passive cavities.

Abstract

CMOS Schmitt trigger is a widely used hysteretic device due to its noise immunity. However, hysteresis by itself incorporate a delay in the device. In order to eliminate the problem of delay and advance the transition, we propose a circuit which works on the principle of proteresis. It is similar to hysteresis but has reverse behavior. Theoretically, when compared to an hysteretic bistable device, a proteretic device has a swapped triggering voltages which leads to twofold speed without altering the ability of noise immunity. The simulation results demonstrate an improvement of approximately 140% in transition time delay when compared to the Schmitt trigger at the cost of area and could be further improved by proper sizing. By using UMC 180 nm CMOS technology, a 0.2 V width proteretic loop has been achieved which signifies the amount of noise immunity it possesses.

Abstract

It has been suggested that there may exist quantum correlations that go beyond entanglement. The existence of such correlations can be revealed by information theoretic quantities such as quantum discord, but not by the conventional measures of entanglement. We argue that a state displays quantumness that can be of local and nonlocal origin. Information theoretic measures not only characterize the nonlocal quantumness but also the local quantumness, such as the “local superposition”. This can be a reason why such measures are nonzero when there is no entanglement. We consider a generalized version of the Werner state to demonstrate the interplay of local quantumness, nonlocal quantumness, and classical mixedness of a state.

Abstract

We find a single parameter family of genuinely entangled three qubit pure states, called the maximally Bell inequality violating states (MBV), which exhibit maximum Bell inequality violation by the reduced bipartite system for a fixed amount of genuine tripartite entanglement quantified by the so called tangle measure. This in turn implies that there holds a complementary relation between the Bell inequality violation by the reduced bipartite systems and the tangle present in the three qubit states, not necessarily pure. The MBV states also exhibit maximum Bell inequality violation by the reduced bipartite systems of the three qubit pure states with a fixed amount of genuine tripartite correlation quantified by the generalized geometric measure, a genuine entanglement measure of multiparty pure states, and the discord monogamy score, a multipartite quantum correlation measure from information theoretic paradigm. The aforementioned complementary relation has also been established for three qubit pure states for the generalized geometric measure and the discord monogamy score respectively. The complementarity between the Bell inequality violation by the reduced bipartite systems and the genuine tripartite correlation suggests that the Bell inequality violation in the reduced two qubit system comes at the cost of the total tripartite correlation present in the entire system.

Abstract

Parallel graph algorithms continue to attract a lot of research attention given their applications to several fields of sciences and engineering. Efficient design and implementation of graph algorithms on modern manycore accelerators has to however contend with a host of challenges including not being able to reach full memory system throughput and irregularity. Of late, focusing on real-world graphs, researchers are addressing these challenges by using decomposition and preprocessing techniques guided by the structural properties of such graphs. In this direction, we present a new GPU algorithm for obtaining an ear decomposition of a graph. Our implementation of the proposed algorithm on an NVidia Tesla K40c improves the state-of-the-art by a factor of 2.3x on average on a collection of real-world and synthetic graphs. The improved performance of our algorithm is due to our proposed characterization that identifies edges of the graph as redundant for the purposes of an ear decomposition. We then study an application of the ear decomposition of a graph in computing the betweenness-centrality values of nodes in the graph. We use an ear decomposition of the input graph to systematically remove nodes of degree two. The actual computation of betweenness-centrality is done on the remaining nodes and the results are extended to nodes removed in the previous step. We show that this approach improves the state-of-the-art for computing betweenness-centrality on an NVidia K40c GPU by a factor of 1.9x on average over a collection of real-world graphs.