Naval Postgraduate School

About: Naval Postgraduate School is a education organization based out in Monterey, California, United States. It is known for research contribution in the topics: Tropical cyclone & Nonlinear system. The organization has 5246 authors who have published 11614 publications receiving 298300 citations. The organization is also known as: NPS & U.S. Naval Postgraduate School.

A very compact s-box for AES

Abstract: A key step in the Advanced Encryption Standard (AES) algorithm is the “S-box.” Many implementations of AES have been proposed, for various goals, that effect the S-box in various ways. In particular, the most compact implementations to date of Satoh et al.[14] and Mentens et al.[6] perform the 8-bit Galois field inversion of the S-box using subfields of 4 bits and of 2 bits. Our work refines this approach to achieve a more compact S-box. We examined many choices of basis for each subfield, not only polynomial bases as in previous work, but also normal bases, giving 432 cases. The isomorphism bit matrices are fully optimized, improving on the “greedy algorithm.” Introducing some NOR gates gives further savings. The best case improves on [14] by 20%. This decreased size could help for area-limited hardware implementations, e.g., smart cards, and to allow more copies of the S-box for parallelism and/or pipelining of AES.

Costate Estimation by a Legendre Pseudospectral Method

Abstract: We present a Legendre pseudospectral method for directly estimating the costates of the Bolza problem encountered in optimal control theory. The method is based on calculating the state and control variables at the Legendre‐Gauss‐Lobatto (LGL) points. An Nth degree Lagrange polynomial approximation of these variables allows a conversion of the optimal control problem into a standard nonlinear programming (NLP) problem with the state and control values at the LGL points as optimization parameters. By applying theKarush ‐Kuhn‐Tucker (KKT) theorem to the NLP problem, we show that the KKT multipliers satisfy a discrete analog of the costate dynamics including the transversality conditions. Indeed, we prove that the costates at the LGL points are equal to the KKT multipliers divided by the LGL weights. Hence, the direct solution by this method also automatically yields the costates by way of the Lagrange multipliers that can be extracted from an NLP solver. One important advantage of this technique is that it allows a very simple way to check the optimality of the direct solution. Numerical examples are included to demonstrate the method.

A User's Guide to the Brave New World of Designing Simulation Experiments

Abstract: The article of record as published may be located at http://dx.doi.org/10.1287/ijoc.1050.0136

Islamic Political Identity in Turkey

Abstract: In November of 2002, the Justice and Development Party swept to victory in the Turkish parliamentary elections. Because of the party's Islamic roots, its electoral triumph has sparked a host of questions both in Turkey and in the West: Does the party harbor a secret Islamist agenda? Will the new government seek to overturn nearly a century of secularization stemming from Kemal Ataturk's early-twentieth-century reforms? Most fundamentally, is Islam compatible with democracy? In this penetrating work, M. Hakan Yavuz seeks to answer these questions, and to provide a comprehensive analysis of Islamic political identity in Turkey. He begins in the early twentieth century, when Kemal Ataturk led Turkey through a process of rapid secularization and crushed Islamic opposition to his authoritarian rule. Yavuz argues that since Ataturk's death in 1938, however, Turkey has been gradually moving away from his militant secularism and experiencing "a quiet Muslim reformation." Islamic political identity is not homogeneous, says Yavuz, but can be modern and progressive as well as conservative and potentially authoritarian. While the West has traditionally seen Kemalism as an engine for reform against "reactionary" political Islam, in fact the Kemalist establishment has traditionally used the "Islamic threat" as an excuse to avoid democratization and thus hold on to power. Yavuz offers an account of the "soft coup" of 1997, in which the Kemalist military-bureaucratic establishment overthrew the democratically elected coalition government, which was led by the pro-Islamic Refah party. He argues that the soft coup plunged Turkey into a renewed legitimacy crisis which can only be resolved by the liberalization of the political system. The book ends with a discussion of the most recent election and its implications for Turkey and the Muslim world. Yavuz argues that Islamic social movements can be important agents for promoting a democratic and pluralistic society, and that the Turkish example holds long term promise for the rest of the Muslim world. Based on extensive fieldwork and interviews, this work offers a sophisticated new understanding of the role of political Islam in one of the world's most strategically important countries.

FIR filter design over a discrete powers-of-two coefficient space

Abstract: FIR digital filters with discrete coefficient values selected from the powers-of-two coefficient space are designed using the methods of integer programming. The frequency responses obtained are shown to be superior to those obtained by simply rounding the coefficients. Both the weighted minimax and the weighted least square error criteria are considered. Using a weighted least square error criterion, it is shown that it is possible to predict the improvement that can be expected when integer quadratic programming is used instead of simple coefficient rounding.