Optimization Based Self-localization for IoT Wireless Sensor Networks

In this paper we propose an embedded optimization framework for the simultaneous self-localization of all sensors in wireless sensor networks making use of range measurements from ultra-wideband (UWB) signals. Low-power UWB radios, which provide time-of-arrival measurements with decimeter accuracy over large distances, have been increasingly envisioned for realtime localization of IoT devices in GPS-denied environments and large sensor networks. In this work, we therefore explore different non-linear least-squares optimization problems to formulate the localization task based on UWB range measurements. We solve the resulting optimization problems directly using non-linear-programming algorithms that guarantee convergence to locally optimal solutions. This optimization framework allows the consistent comparison of different optimization methods for sensor localization. We propose and demonstrate the best optimization approach for the self-localization of sensors equipped with off-the-shelf microcontrollers using state-of-the-art code generation techniques for the plug-and-play deployment of the optimal localization algorithm. Numerical results indicate that the proposed approach improves localization accuracy and decreases computation times relative to existing iterative methods

High Throughput Implementations of the RC6 Block Cipher Using Virtex-E and Virtex-II Devices

This short paper is devoted to the study of effective hardware architectures for the RC6 block cipher using Virtex-E and Virtex-II FPGA devices. The key point of the implementation is the design of an arithmetic operator computing f(X)=(X(2X+1))2^w. Significant speed and area improvements are obtained by taking full advantage of the small multiplier blocks available in Virtex-II devices

Multiplication-addition modulaire: algorithmes itératifs et implantations sur FPGA

This paper describes several improvements of an iterative algorithm for modular multiplication originally proposed by Jeong and Burleson. A first modification of the recurrence relation allows us to implement a fused multiply and add unit. Then, we show how to reduce the circuit area by a factor two when the operator offers the possibility to choose the modulo among a set m_1, m_2,, m_q. A new iterative algorithm making the implementation of modular exponentiation easier is eventually discussed. For 16-bit numbers, our operators perform for instance 6 millions of operations per second on a Virtex-E device while only requiring 17 slices

Modular Multiplication for FPGA Implementation of the IDEA Block Cipher

The IDEA block cipher is a symmetric-key algorithm which encrypts 64-bit plaintext blocks to 64-bit ciphertext blocks, using a 128-bit secret key. The security of IDEA relies on combining operations from three algebraic groups: integer addition modulo 2^n, bitwise exclusive or of two n-bit words, and integer multiplication modulo (2^n+1) which is the critical arithmetic operation of the block cipher. In this paper, we investigate three algorithms based on a small multiplication with a subsequent modulo correction. They are particularly well suited for the latest FPGA devices embedding small multiplier blocks, like the Virtex-II family. We also consider a multiplier based on modulo (2^n+1) adders. Several architectures of the IDEA block cipher are then described and compared from different point of view: throughput to area ratio or adequation with feedback and non-feedback chaining modes. Our fastest circuit achieves a throughput of 8.5 Gb/s, which is, to our knowledge, the best rate reported in the literature

Kidney structure of a euryhaline mammal, the Cape clawless otter (Aonyx capensis)

The Cape clawless otter (Aonyx capensis) is one of the few species of mammals that occur in both freshwater and marine habitats, and it therefore must be able to tolerate the high rates of water flux typical of aquatic animals as well as the desiccating effects of seawater. The clawless otter has paired, discrete multirenculate kidneys (total mass = 172 g) comprised of both unipapillary and bipapillary renculi weighing an average of 2.6 and 3.2 g, respectively, The average thickness of the cortex is 2.3 mm, and thicknesses of the outer and inner medulla are 2.4 and 6.4 mm, respectively. These measurements and the overall structure of the kidney of the Cape clawless otter are intermediate between those of freshwater and marine mammals

La pédagogie différenciée :: le point de vue d'enseignants partagés entre conviction et interrogation

J’imaginais bien qu’enseigner à des élèves qui ont des capacités et des modes d’apprentissage différents est un défi complexe. Si le modèle théorique de la pédagogie différenciée s’impose presque comme une évidence pour faire face à cette hétérogénéité, sa mise en oeuvre en classe suscite beaucoup de questionnements et de réserves. Ma réflexion s’appuie sur un questionnaire envoyé à vingt enseignants pour voir comment ils agissent sur le terrain par rapport à la théorie, quels avantages ils voient à pratiquer la différenciation pédagogique et quels problèmes ils rencontrent au quotidien. Adapter, varier les dispositifs, les modalités, les supports d’enseignement ainsi que mettre au centre l’élève et son activité pour favoriser ses apprentissages demande beaucoup d’investissement de la part des enseignants et ceux-ci ne se sentent pas toujours en mesure de le faire. Ce mémoire m’a permis de réaliser que le recours à la différenciation est indispensable. C’est une attitude pédagogique et pas seulement des techniques. Son application est un compromis qui tient compte de la réalité de l’enseignant, du contexte classe et de la matière à enseigner. Pour favoriser son application, je ne suis pas surprise que les enseignants sollicitent une aide sous forme d’analyse et de réflexion au sujet de leurs pratiques dans le cadre de groupes professionnels plutôt que des apports théoriques académiques