Inside Front Cover: The Elastic Properties and Plastic Behavior of Two‐Dimensional Polymer Structures Fabricated by Laser Interference Lithography (Adv. Funct. Mater. 10/2006)

The probing of the micromechanical properties within a two‐dimensional polymer structure with sixfold symmetry fabricated via interference lithography reveals a nonuniform spatial distribution in the elastic modulus “imprinted” with an interference pattern in work reported by Tsukruk, Thomas, and co‐workers on p. 1324. The image prepared by M. Lemieux and T. Gorishnyy shows how the interference pattern is formed by three laser beams and is transferred to the solid polymer structure. The elastic and plastic properties within a two‐dimensional polymer (SU8) structure with sixfold symmetry fabricated via interference lithography are presented. There is a nonuniform spatial distribution in the elastic modulus, with a higher elastic modulus obtained for nodes (brightest regions in the laser interference pattern) and a lower elastic modulus for beams (darkest regions in the laser interference pattern) of the photopatterned films. We suggest that such a nonuniformity and unusual plastic behavior are related to the variable material properties “imprinted” by the interference pattern.     

Design procedure of class-E amplifier for off-nominal operation at 50% duty ratio

Design equations for satisfying the off-nominal operating condition [i.e., only the zero-voltage switching (ZVS) condition] of the Class-E amplifier with a linear shunt capacitance at a duty ratio D=0.5 are derived. A new parameter s (V/s), called the slope of switch voltage when the switch turns on is introduced to obtain an image of the distance from the nominal conditions. By examining off-nominal Class-E operation degree of the design freedom of the Class-E amplifier increases by one. In addition various amplifier parameters such as operating frequency, output power, and load resistance range can be set as design specifications. For example, the peak switch voltage and switch current can be taken into account in the design procedure. Examples of a design procedure of the Class-E amplifier for off-nominal operation are given. The theoretical results were verified with PSpice simulation and experiments.     

Mobile Device Security Using Transient Authentication

Mobile devices are vulnerable to theft and loss due to their small size and the characteristics of their common usage environment. Since they allow users to work while away from their desk, they are most useful in public locations and while traveling. Unfortunately, this is also where they are most at risk. Existing schemes for securing data either do not protect the device after it is stolen or require bothersome reauthentication. Transient Authentication lifts the burden of authentication from the user by use of a wearable token that constantly attests to the user's presence. When the user departs, the token and device lose contact and the device secures itself. We show how to leverage this authentication framework to secure all the memory and storage locations on a device into which secrets may creep. Our evaluation shows this is done without inconveniencing the user, while imposing a minimal performance overhead     

A CMOS multichannel 10-Gb/s transceiver

We describe a CMOS multichannel transceiver that transmits and receives 10 Gb/s per channel over balanced copper media. The transceiver consists of two identical 10-Gb/s modules. Each module operates off a single 1.2-V supply and has a single 5-GHz phase-locked loop to supply a reference clock to two transmitter (Tx) channels and two receiver (Rx) channels. To track the input-signal phase, the Rx channel has a clock recovery unit (CRU), which uses a phase-interpolator-based timing generator and digital loop filter. The CRU can adjust the recovered clock phase with a resolution of 1.56 ps. Two sets of two-channel transceiver units were fabricated in 0.11-/spl mu/m CMOS on a single test chip. The transceiver unit size was 1.6 mm /spl times/ 2.6 mm. The Rx sensitivity was 120-mVp-p differential with a 70-ps phase margin for a common-mode voltage ranging from 0.6 to 1.0 V. The evaluated jitter tolerance curve met the OC-192 specification.     

Web Services Architecture

The underlying need for Web Services has been demonstrated by their early adoption and rapid evolution during the last few years. This evolution has resulted in a number of specifications being proposed that at first glance seem independent of one another. The current immaturity of the base technology and the growing number and diversity of specifications related to Web Services is sometimes seen as a barrier to developers attempting to combine them to create a working piece of software. For some, the apparent lack of stability and coherence in the specifications even raises the question of the real long-term viability and value of the technology. This document puts those specifications into perspective by describing the set of interoperable XML protocols that are the foundation of building interoperable systems, middleware, and applications. This revised version was published online in July 2006 with corrections to the Cover Date.     

Metastable phase relation and phase equilibria in the Cr2O3-Fe2O3 system

In order to ascertain the metastable phase relation in the Cr₂O₃-Fe₂O₃ system, the existing phases were investigated by X-ray analysis using samples obtained by heating the coprecipitated powders for 1 h at 600–1000°C. There was a metastable two-phase region of Cr₂O₃-rich (CC) and Fe₂O₃-rich (FC) phases below about 940°C. Equilibrium state of 1:1 composition at 600–900°C was considered to be a single phase of the corundum solid solution. The metastable two-phase CC + FC region was suggested to appear probably due to the compositional inhomogeneity in the coprecipitated powders.     

Search for high-performance probe-fed stacked patches using optimization

High-performance circular probe-fed stacked patch antenna designs are explored through the use of numerical optimization. New trends are sought to aid understanding and to suggest novel solutions. We describe the optimization technique, present a new design trend relating efficiency and bandwidth to the choice of substrate dielectric, and propose and demonstrate a novel, optimized antenna achieving 33% bandwidth whilst maintaining greater than 80% surface wave efficiency.     

L’optimisation des réseaux cellulaires assistée par ordinateur: le logiciel RNO (Radio Network Optimisation)

Quality of service has become today a major concern for operators of mobile communication networks. The massive development of networks and strong competition between operators has lead to the necessary and daily follow-up of network quality of service, a key factor for its subscriber’s fidelity. This article aims at presenting the optimization methodology and proposes its illustration with a case of RNO (Radio Network Optimisation) software usage, one of the Alcatel optimization toolchain component. After a short presentation of cellular network, the optimization basic principles are described. RNO software and its main functionnalities are then detailed before a last part dedicated to a real case of optimization done with RNO software.