A survey on software checkpointing and mobility techniques in distributed systems

This paper has two purposes. First, it shows that existing solutions employing checkpointing and mobility in distributed applications, fix, at design time, the types and the techniques of checkpointing and mobility to be employed at runtime. Second, it provides policies allowing the dynamic selection of checkpointing and mobility techniques according to the execution environment. For that, this paper presents checkpointing and mobility techniques to evaluate them in order to identify their advantages and their shortcomings, and then determine the appropriate execution conditions in which a specific mobility technique becomes beneficial. This investigation will allow in assisting adaptation plans' generation and promoting future research in the area of self‐adaptivity of distributed applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Calculation of the electrical properties of pin power diodes at high current densities by the method of finite elements

Contents In the presented paper the method of finite elements has been used to determine the solution of the transport equation in the middle region of pin diodes. Quasineutrality in thei-region and constant recombination parameters in the end regions have been assumed. Under static conditions the influence of the high injection effects—first separately and then combined—on the carrier distribution at 3000 A/cm² and on the current voltage characteristic has been studied. The carrier-carrier scattering produces the highest increase of the forward voltage drop of pin diodes. The recombination in the end regions plays a significant role too, while the Auger recombination becomes important mainly at extremly high current densitics.

---

Berechnung der elektrischen Eigenschaften von pinDioden im Hochstrombereich nach der Methode der finiten Elemente

Übersicht In dieser Arbeit wird die Methode der finiten Elemente zur numerischen Lösung der Transportgleichung im Mittelgebiet einer pin-Diode angewandt. Dabei werden Quasineutralität in deri-Zone und konstante Rekombinationsparameter in den Endgebieten vorausgesetzt. Bei statischer Belastung der pin-Diode wurde der Einfluß der Hochinjektionseffekte—zunächst einzeln und dann gemeinsam—auf die Trägerverteilung bei 3000 A/cm² und auf die Stromspannungskennlinie untersucht. Die Träger-Träger-Streuung ergibt den größten Beitrag zur Erhöhung der Durchlaßspannung von pin-Dioden. Daneben spielt die Endzonenrekombination ebenfalls eine bedeutende Rolle. Die Auger-Rekombination macht sich erst bei schr hohen Stromdichten stark bemerkbar.

     

Adaptive cumulative sum charts with the adaptive runs rule

Adaptive cumulative sum (ACUSUM) charts, which adjust the reference value dynamically based on estimated shift size, provide good performance in detecting a range of mean shifts. However, when the range is wide, ACUSUM may not perform well for small shifts over the range. An adaptive runs rule, which is motivated by the concept of supplementary runs rule, is proposed, in order to make control charts more sensitive to small mean shifts. The adaptive runs rule assigns scores to consecutive runs based on the estimated shift size of the mean. The ACUSUM chart is supplemented with the adaptive runs rule to enhance its sensitivity in detecting small mean shifts. The average run length performance of the ACUSUM chart with the adaptive runs rule is compared with those of cumulative sum and variants of adaptive charts including ACUSUM. The experimental results reveal that the ACUSUM chart with the adaptive runs rule achieves superior detection performance over a wide range of mean shifts.     

Utilization of composite’s tensile properties for energy absorbing systems

This idea was inspired by the fact that huge energy absorption capability can be achieved if the longitudinal properties of composite structures are being utilized. This can only be done if the energy absorbing system postfailure scenario is mitigated to be tearing failure mechanism. In this paper, friction, crazing, circumferential expansion and tearing failure mechanisms were introduced and applied successfully to control the response of energy absorbing system to the applied load. The system was designed by slipping a solid cone into composite cone. The semi-cone angles used were 8°, 12°, 16° and 20°. The cone height and bottom diameter were kept constant for all cases as 100 mm and 76.2 mm, respectively. Force–stroke curves and deformation histories of typical specimens are presented and discussed. The results demonstrated that at first crush stage the energy is dissipated in the form of friction and crazing and the conical responded in an elastic manner, while the post-crush stage is dominated by tearing failure mechanisms.     

Performance analysis of space-time MMSE multiuser detection for coded DS-CDMA systems in multipath fading channels

This paper investigates the use of convolutional coding in space-time minimum mean-square-error (MMSE) multiuser-based receivers over asynchronous multipath Rayleigh fading channels. We focus on the performance gain attained through error control coding when used with binary-phase-shift-keyed modulation (BPSK) and multiuser access based on direct sequence-code-division multiple access (DS-CDMA). In our analysis, we derive an approximation for the uncoded probability of bit-error in multipath fading channels. This bit-error rate (BER) approximation is shown to be very accurate when compared to the exact performance. For a convolutionally coded system, we obtain a closed form expression for the bit-error rate upper bound. This error bound is noted to be tight as the number of quantization levels increased beyond eight. Using our theoretical results, we obtain an estimate for the achieved user-capacity that accrues due to error control coding. It is found that using convolutional coding with 3-bit soft-decision decoding, a user-capacity gain as much as 300% can easily be achieved when complete fading state information plus ideal channel interleaving are assumed.     

Stochastic analysis of interphase effects on elastic modulus and yield strength of nylon 6/clay nanocomposites

The multifunctional properties of polymer clay nanocomposites (PCNs) can be related to the interaction of clays, polymer and interphase region. Several experimental, analytical and numerical studies have been conducted to characterize the mechanical behavior of PCNs. The elastic behavior of PCNs is well documented in the literature but their other material properties like yield strength are rather vague. On the other hand, the variation of material parameters and the stochastic nature of interphase region hinder the use of deterministic methods. In this study, a stochastic analysis along with a hierarchical multiscale method is used to analyze the effect of interphase properties on the macroscopic properties of PCNs. Since the interphase layer is expected to be weaker than the polymer matrix, a weakening coefficient is defined to describe the interphase properties based on the matrix properties. This weakening coefficient and the interphase thickness are considered as the stochastic inputs. The elastic modulus and yield strength of nylon 6/clay nanocomposites are calculated using the stochastic multiscale framework. The uncertainty propagation and sobol sensitivity analysis are performed to study the effect of random inputs on the elastic modulus and yield strength of PCNs. Despite the wide range of input variations, the accuracy of the proposed stochastic multiscale framework for the prediction of the PCNs properties is estimated by validating our results against the available experimental data in the literature.

     

Multi-instance cancellable biometrics schemes based on generative adversarial network

The main role of cancellable biometric schemes is to protect the privacy of the enrolled users. The protected biometric data are generated by applying a parametrized transformation function to the original biometric data. Although cancellable biometric schemes achieve high security levels, they may degrade the recognition accuracy. One of the mostwidely used approaches to enhance the recognition accuracy in biometric systems is to combine several instances of the same biometric modality. In this paper, two multi-instance cancellable biometric schemes based on iris traits are presented. The iris biometric trait is used in both schemes because of the reliability and stability of iris traits compared to the other biometric traits. A generative adversarial network (GAN) is used as a transformation function for the biometric features. The first scheme is based on a pre-transformation feature-level fusion, where the binary features of multiple instances are concatenated and inputted to the transformation phase. On the other hand, the second scheme is based on a post-transformation feature-level fusion, where each instance is separately inputted to the transformation phase. Experiments conducted on the CASIA Iris-V3-Internal database confirm the high recognition accuracy of the two proposed schemes. Moreover, the security of the proposed schemes is analyzed, and their robustness against two well-known types of attacks is proven.

     

Labeled flow-based dataset of ICMPv6-based DDoS attacks

Neural Computing and Applications - DDoS attacks that depend on Internet Control Message Protocol version 6 (ICMPv6) are one of the most commonly performed IPv6 attacks against today’s IPv6...     

Implementation of the beam reversal technique on compact cesiumclocks: towards an improvement in accuracy

Reports the evaluation of the residual phase difference ▵φ in a short (18 cm) Ramsey cavity by implementing the beam reversal technique in an optically pumped cesium beam clock. ▵φ is measured to be 21 ±1.5 μrad, allowing a more accurate evaluation of the frequency performance of this small cesium clock. Finally, the clock accuracy is equal to 1.1·10^-13     

Performance of zero-forcing detectors over MIMO flat-correlated Ricean fading channels

The bit error rate (BER) performance of the zero-forcing (ZF) receiver over transmit-correlated flat Ricean fading channels is investigated. In particular, for a multiple-input multiple-output (MIMO) channel with M transmit and N receive antennas, an approximation for the average BER of each substream is derived. Then the system performance in receive-correlated flat Ricean fading channels is addressed. In this case, it is shown that the performance, when N ? M, is the same as that of transmit-correlated flat Ricean fading channels. A closed-form expression for the optimum transmit correlation coefficient, which achieves the maximum capacity (i.e. uncorrelated case), is also derived. As a result, a significant capacity gain is achieved by exploiting the knowledge of the Ricean channel. Extensive simulations are presented to validate and demonstrate the performance gain with different system parameters.