Survey and comparison of message authentication solutions on wireless sensor networks

Security is an important concern in any modern network. This also applies to Wireless Sensor Networks (WSNs), especially those used in applications that monitor sensitive information (e.g., health care applications). However, the highly constrained nature of sensors imposes a difficult challenge: their reduced availability of memory, processing power and energy hinders the deployment of many modern cryptographic algorithms considered secure. For this reason, the choice of the most memory-, processing- and energy-efficient security solutions is of vital importance in WSNs. To date, a number of extensive analyses comparing different encryption algorithms and key management schemes have been developed, while very little attention has been given to message authentication solutions. In this paper, aiming to close this gap, we identify cipher-based Message Authentication Codes (MACs) and Authenticated Encryption with Associated Data (AEAD) schemes suitable for WSNs and then evaluate their features and performance on a real platform (TelosB). As a result of this analysis, we identify the recommended choices depending on the characteristics of the target network and available hardware.     

Improving user content privacy on social networks using rights management systems

Currently, millions and millions of users are using online social networks to share their thoughts, experiences and content with online friends. Documents, videos, music and pictures are shared online, relying on the privacy and security controls offered by the social network platforms, with little control from the end user. This creates serious privacy concerns, since the control over the content shared online on the social network is out of the hands of the user. In this paper, the authors propose an approach for content privacy shared on social networks that is user-centric and not based on the social network platform. In order to achieve that, an architecture based on a rights management platform capable of enforcing the necessary security and privacy mechanisms that extend the original controls provided by the social network platform will be presented. That way, users will be able to control their privacy settings and protect their own content, even when they are no longer part of the social network (suspending or deleting its account).     

Programmable SC Biquad Using One Single Capacitor Bank

This paper presents a new technique for programming SC circuits using a single time-multiplexed capacitor bank, achieving a significant reduction in capacitance area. Simulation and experimental results obtained with a programmable biquad low pass filter show the validity of the proposed method.Antonio Torralba was born in Seville, Spain. He received the electrical engineering and Ph.D. degrees from the University of Seville, Seville, Spain, in 1983 and 1985, respectively. Since 1983, he has been with the Department of Electronic Engineering, School of Engineering, University of Seville, where he has been an Assistant professor, Associate Professor (1987), and Professor (1996). He has published 30 papers in journals and more than 80 papers in conferences. His research interests are in the design and modeling of low-voltage analog circuits, analog and mixed-signal design, analog to digital conversion, and electronic circuits and systems with application to control and communication.Alfredo Pérez Vega-Leal was born in Seville, Spain. He received the Electrical Engineering and Ph.D. degrees from the University of Seville, Seville, Spain, in 1998 and 2003, respectively. Since 1995, he has been with the Department of Electronic Engineering, School of Engineering, University of Seville, as research student and became an Associate Professor in 1999. His research interests are related to low-voltage low-power analog circuit design, A/D and D/A conversion.Ramón González Carvajal was born in Seville, Spain. He received the Electrical Engineering and Ph.D. degrees from the University of Seville, Seville, Spain, in 1995 and 1999, respectively. Since 1996, he has been with the Department of Electronic Engineering, School of Engineering, University of Seville, where he has been an Associate Professor (1996), and Professor (2002). He has published more than 100 papers in International Journals and Conferences. His research interests are related to low-voltage low-power analog circuit design, A/D and D/A conversion, and analog and mixed signal processing.     

Adaptive Resource Sharing Strategies for UMTS Multiservice Mobiles

In this paper, a multiservice transmission scheme which joints voice, video, interactive game and signaling is evaluated for the dedicated channel of the Universal Mobile Telecommunications System. The transmission rate for each service is determined by means of an adaptive transport format selection. In the UMTS standard, this selection is based on power allocation provided by radio resource controller, trying to match the Eb/No requirements of the individual services. An appropriate selection of the individual rates of each multiplexed service, taking into account its particular QoS requirements, will provide a more efficient resource management than the transmission only restricted to power allocation. For this purpose, we propose and evaluate a new selection strategy based on buffer occupation, delay requirements and target bit rate keeping power constraints that intends to improve the basic operation trying to minimize the impact of the whole network. Video and game services are multiplexed in upper layers (logical channels) sharing a common transmission rate (transport channel). In this paper, it is proposed a new strategy to share the transmission rate set for this transport channel between both services taking into account their particular requirements. Results show that considering delay constraints provides a more balanced performance of the multiplexed services.     

Residual stress in hydroxyapatite coating: nonlinear analysis and high-energy synchrotron measurements

The thermal deposition of hydroxyapatite (HA) on titanium alloy substrate (Ti-6A1-4V) leads to a structure that has very good osseointegration properties. However, clinical failures have been occasionally reported at the interface between substrate and coating. Lifetime is the main parameter in such prostheses; therefore, in order to improve their quality, it is necessary to evaluate the level of stresses near the interface. The high-energy synchrotron radiation combines the advantages of a bulk analysis and reduced volume of the gauge. The objective of our study was to calculate the residual stress using a nonlinear finite-element model and to measure residual stress level near the interface, in the hydroxyapatite coating and in titanium alloy substrate with a nondestructive and high-resolution experiment. The high-energy synchrotron radiation of the BM16 beam-line at ESRF (Grenoble-France) was used with a resolution of down to 10 micrometers. The experimental measurements validate the results found by means of nonlinear finite-element analysis of the plasma spraying induced stress.     

用于电源测试的精确压控电流阱

为了检测潜在的电源缺陷,必须进行动态和静态测试。这里的简单电流阱可测试低到中功率电源和恒压源。在该应用中,在输入电压范围为0V～5V,电源电压最高为20V时,电流阱可吸收0A～1.5A的电流。该电路的基本部件为一个精密运放IC1,采用Texas Instruments的OPA277。该器件特点为：最大输入偏置电压仅为100μV,最大输入偏置电流为4nA,在-40℃-＋85℃温度范围内温漂较低（图1）。运放IC将其正输入电压与检测电阻RSENSE上的电压进行比较。     

Some statistical properties of mathematical morphology

Analyzes the statistical properties of the basic binary and multilevel morphological operations with both 1-D and 2D structuring elements. Very simple expressions for the output distribution of erosion and opening are derived in the case of any independent identically or nonidentically distributed inputs. The probability relations between erosion and dilation, also between opening and closing, are developed. The output expectation bias and variances are analyzed and computed to show the efficiency of morphological operations for noise supression. As applications of theoretical results, the effects of the morphological operations on noisy signals are illustrated by several examples. The study reveals certain interesting phenomena. For example, the output variances of opening for some input distributions are greater than those of erosion, and morphological operations perform better than median filters in edge preservation     

Effects of Phonon Confinement on Anomalous Thermalization,Energy Transfer,and Upconversion in Ln3+‐Doped Gd2O3 Nanotubes

There is a growing interest in understanding how size‐dependent quantum confinement affects the photoluminescence efficiency, excited‐state dynamics, energy‐transfer and thermalization phenomena in nanophosphors. For lanthanide (Ln³⁺)‐doped nanocrystals, despite the localized 4f states, confinement effects are induced mostly via electron–phonon interactions. In particular, the anomalous thermalization reported so far for a handful of Ln³⁺‐doped nanocrystals has been rationalized by the absence of low‐frequency phonon modes. This nanoconfinement may further impact on the Ln³⁺ luminescence dynamics, such as phonon‐assisted energy transfer or upconversion processes. Here, intriguing and unprecedented anomalous thermalization in Gd₂O₃:Eu³⁺ and Gd₂O₃:Yb³⁺,Er³⁺ nanotubes, exhibiting up to one order of magnitude larger than previously reported for similar materials, is reported. This anomalous thermalization induces unexpected energy transfer from Eu³⁺ C₂ to S₆ crystallographic sites, at 11 K, and ²H_11/2 → ⁴I_15/2 Er³⁺ upconversion emission; it is interpreted on the basis of the discretization of the phonon density of states, easily tuned by varying the annealing temperature (923–1123 K) in the synthesis procedure, and/or the Ln³⁺ concentration (0.16–6.60%).