On the dynamic rounding-off in analogue and RF optimal circuit sizing

Frequently used approaches to solve discrete multivariable optimisation problems consist of computing solutions using a continuous optimisation technique. Then, using heuristics, the variables are rounded-off to their nearest available discrete values to obtain a discrete solution. Indeed, in many engineering problems, and particularly in analogue circuit design, component values, such as the geometric dimensions of the transistors, the number of fingers in an integrated capacitor or the number of turns in an integrated inductor, cannot be chosen arbitrarily since they have to obey to some technology sizing constraints. However, rounding-off the variables values a posteriori and can lead to infeasible solutions (solutions that are located too close to the feasible solution frontier) or degradation of the obtained results (expulsion from the neighbourhood of a ‘sharp’ optimum) depending on how the added perturbation affects the solution. Discrete optimisation techniques, such as the dynamic rounding-off technique (DRO) are, therefore, needed to overcome the previously mentioned situation.

In this paper, we deal with an improvement of the DRO technique. We propose a particle swarm optimisation (PSO)-based DRO technique, and we show, via some analog and RF-examples, the necessity to implement such a routine into continuous optimisation algorithms.     

LTE Advanced Relaying Standard: A Survey

Long term evolution (LTE) Advanced is a well designed system that meets the requirements of 4G cellular systems. Its standard specification has been lately released. One of its main features is supporting relaying topology inspired from ad hoc multihop networks. This paper is a survey upon the relaying architecture of LTE Advanced standard based on 3GPP Release 10 specifications. A comparison with other relaying architectures, i.e. IEEE 802.16m and IEEE 802.11s is handled. The originality of this work is in involving comparison with multihop architecture supported by IEEE 802.11s based wireless mesh networks. Several similarities are noted and differences are pointed out.     

Chams: Churn-aware overlay construction for media streaming

Overlay networks support a wide range of peer-to-peer media streaming applications on the Internet. The user experience of such applications is affected by the churn resilience of the system. When peers disconnect from the system, streamed data may be delayed or lost due to missing links in the overlay topology. In this paper, we explore a proactive strategy to create churn-aware overlay networks that reduce the potential of disruptions caused by churn events. We describe Chams, a middleware for constructing overlay networks that mitigates the impact of churn. Chams uses a ??hybrid?? approach??it implicitly defines an overlay topology using a gossip-style mechanism, while taking the reliability of peers into account. Unlike systems for overlay construction, Chams supports a variety of topologies used in media streaming systems, such as trees, multi-trees and forests. We evaluate Chams with different topologies and show that it reduces the impact of churn, while imposing only low computational and message overheads.     

A quantitative assessment of security risks based on a multifaceted classification approach

Information systems and cloud computing infrastructures are frequently exposed to various types of threats. Without detection and prevention mechanisms, the threats can materialize and cause different types of damages that usually lead to significant financial losses. The threats arise from a complex and multifaceted environment. Currently, organizations are struggling to identify the threats to their information assets and assess the overall damage they might inflict to their systems. In order to empower mangers to better plan for shielding their information systems, the paper presents two main contributions. First, a new approach to threat classification that leads to a security assessment model that is systematic, extendable, and modular. Second, a quantitative analysis of information systems based on the model.

     

Deployment and validation of out of band IP traceback approach (OBTA) in wireless mesh network

Wireless mesh networks (WMNs) have acquired recently enormous attention and momentum; therefore, security aspects have been a fundamental concern for them. Among catastrophic threats on WMNs, Denial‐of‐Service attacks that have become a severe danger because of their plug‐and‐play structural design. Unfortunately, preventing a Denial‐of‐Service attack presents a challenging issue. This fact is induced with the appearance of the source IP addresses spoofing. The resolution key of this issue is to reveal the attack source based on the path through which the attack packet passes. For this, many researchers in IP traceability field propose various methods and techniques to deal with the issue. In this article, we conceive a novel approach named out of band IP traceback approach in WMN (IEEE 802.11s). We create a new architecture using signaling messages for discovering the real source(s) of IP packets. Our solution is based on a security‐oriented signaling protocol. This protocol allows specialized signaling entities to communicate via reliable signaling information. This fact permits us to perform a simple and efficient traceback. In our novel approach, we use 2 radios: the first one transmits normal data packets whereas the second is reserved to exchange IP traceback information. The performance of the proposed scheme is analyzed via simulation analysis using the Network Simulator 3. The simulation results show that our scheme is efficient in dealing with the traceback problem in WMN environments.     

Deep Learning Based Application for Indoor Scene Recognition

Neural Processing Letters - Recognizing indoor scene and objects and estimating their poses present a wide range of applications in robotic field. This task becomes more challenging especially in...     

Structural,optical, and electrical properties of In<Subscript>2</Subscript>S<Subscript>3</Subscript>:Sn thin films grown by chemical bath deposition on Pyrex

Sn-doped In₂S₃ thin films are deposited on Pyrex. Tin is incorporated in the solution using SnCl₂·2H₂O. The properties of the films are investigated by X-ray diffraction (XRD), atomic force microscopy, scanning electron microscopy, spectrophotometry, and thermally stimulated current (TSC) measurements. XRD analysis reveals that the films become almost amorphous when tin exceeds well determined optimum quantity. The investigation of optical properties shows that the band gap depends on the value of the Sn concentration. It is also observed that upon adding the optimum quantity of tin, the maximum of the TSC intensity increased by 2 orders of magnitude. These results are discussed with respect to introduce the effect of tin incorporated in the physical properties.     

Analysis of the interaction between turbulent combustion and thermal radiation using unsteady coupled LES/DOM simulations

Radiation exchanges must be taken into account to improve the prediction of heat fluxes in turbulent combustion. The strong interaction with turbulence and its role on the formation of polluting species require the study of unsteady coupled calculations using Large Eddy Simulations (LESs) of the turbulent combustion process. Radiation is solved using the Discrete Ordinate Method (DOM) and a global spectral model. A detailed study of the coupling between radiative heat transfer and LES simulation involving a real laboratory flame configuration is presented. First the impact of radiation on the flame structure is discussed: when radiation is taken into account, temperature levels increase in the fresh gas and decrease in the burnt gas, with variations ranging from 100 K to 150 K thus impacting the density of the gas. Coupling DOM and LES allows to analyze radiation effects on flame stability: temperature fluctuations are increased, and a wavelet frequency analysis shows changes in the flow characteristic frequencies. The second part of the study focuses on the Turbulence Radiation Interaction (TRI) using the instantaneous radiative fields on the whole computational domain. TRI correlations are calculated and are discussed along four levels of approximation. The LES study shows that all the TRI correlations are significant and must be taken into account. These correlations are also useful to calculate the TRI correlations in the Reynolds Averaged Navier–Stokes (RANS) approach.     

An Evaluation of RetinaNet on Indoor Object Detection for Blind and Visually Impaired Persons Assistance Navigation

Neural Processing Letters - Indoor object detection presents a computer vision task that deals with the detection of specific indoor classes. This task attracts a lot of attention, especially in...