Bandwidth reservation in mobile adhoc networks

International audienceThe bandwidth reservation is one of most adopted solutions to meet QoS requirements in 802.11 ad hoc networks. The efficiency of these solutions depends on the accuracy of their estimations of available bandwidth; otherwise, their application can be catastrophic on networks. Therefore, accurate bandwidth estimation is fundamental, where each networks characteristic must be taken into consideration, including mobility and medium sharing. Current solutions do not take into account all networks characteristics, resulting to wrong bandwidth estimations and QoS violations. In this paper, we present a new approach for bandwidth reservation-Accurate Bandwidth Reservation (ABR)-which embeds an improved method of available bandwidth measurement, where all criteria of such networks are considered. Evaluation of ABR is performed by simulations and comparisons with some existing approaches

Optimal RoadSide Units Distribution Approach in Vehicular Ad hoc Network

A vehicular ad hoc network is a particular type of ad hoc mobile network. It is characterized by high mobility and frequent disconnection between vehicles. For this, the roadside units (RSUs) deployment permits to enhance the network connectivity. The objective of this work is to provide an optimized RSUs placement for enhancing the network connectivity and maximizing the accident coverage with reducing the deployment cost. In this paper, we propose our approach called Optimized RoadSide units Deployment (ORSD). The proposed approach comprises a two-step, in the first step, ORSD finds the RSUs candidate locations based on network density and connectivity. We calculated the connectivity of each segment based on speed and arrival information’s.  The second step permit to find the optimal solution of our proposed objective function. The objective function permits to enhance the network connectivity and maximizing the accident coverage.  To find the optimal solution of our objective function is an NP-complete problem of order o(n²) .  Therefore, we propose to solve this problem in two phases, so that it becomes a simple linear problem to solve. The ORSD is proposed for urban and high way scenarios. The extensive simulation study is conducted in order to assess the effectiveness of the proposed approach. We use the Simulator of Urban MObility (SUMO) for generating different traffic scenarios. We develop scripts to extract different information as density, speed and travel time in each segment. Then, we develop an algorithm to calculate connectivity probability for each segment. Then, we implement our objective function to finds optimal RSUs positions in terms of connectivity, accident cover and cost

Recurrence of ventricular arrhythmias in ischaemic secondary prevention implantable cardioverter defibrillator recipients: long-term follow-up of the Leiden out-of-hospital cardiac arrest study (LOHCAT)

Aims to assess the long-term rate of mortality and the recurrence of potentially life-threatening ventricular arrhythmias in secondary prevention implantable cardioverter defibrillator (ICD) patients and to construct a model for baseline risk stratification.Methods and resultsSince 1996, all patients with ischaemic heart disease, receiving ICD therapy for secondary prevention of sudden death, were included in the current study. Patients were evaluated at implantation and during long-term follow-up. A total of 456 patients were included in the analysis and followed for 54 ± 35 months. During follow-up, 100 (22) patients died and ICD therapy was noted in 216 (47) patients, of which 138 (30) for fast, potentially life-threatening ventricular arrhythmia. Multivariate analysis revealed a history of atrial fibrillation or flutter (AF), ventricular tachycardia as presenting arrhythmia, and wide QRS and poor left ventricular ejection fraction as independent predictors of life-threatening ventricular arrhythmias. The strongest predictor was AF with a hazard ratio of 2.1 (95 confidence interval 1.3-3.2). On the basis of the available clinical data, it was not possible to identify a group which exhibited no risk on recurrence of potentially life-threatening ventricular arrhythmias.ConclusionIschaemic secondary prevention ICD recipients exhibit a high recurrence rate of potentially life-threatening ventricular arrhythmias. Factors that increase risk can be identified but, even with these factors, it was not possible to distinguish a recurrence-free group

Prevalence of peripapillary choroidal neovascular membranes (PPCNV) in an elderly UK population—the Bridlington eye assessment project (BEAP): a cross-sectional study (2002–2006)

© 2018, The Royal College of Ophthalmologists. Purpose: There is paucity of data on the epidemiology of peripapillary choroidal neovascularisartion (PPCNV). Our aim was to determine prevalence of PPCNV in the elderly UK population of Bridlington residents aged ≥65 years. Methods: Eyes with PPCNV in the Bridlington eye assessment project (BEAP) database of 3475 participants were analysed. PPCNV outline was drawn, its area measured, and clock-hour involvement of disc circumference recorded. Location and shortest distance from the lesion edge to fovea were recorded. Masked grading for age-related maculopathy (ARM)/reticular pseudodrusen (RPD) within the ETDRS grid was assigned for each eye using a modified Rotterdam scale. Peripapillary retinal pigment epithelial (RPE) changes/drusen were recorded. Visual acuity (VA) and demographic details analysed separately were merged with grading data. Results: PPCNV were identified in ten subjects, and were bilateral in two (20%), a population prevalence of 0.29%, and 0.06% bilaterality. Gender-specific prevalence were 0.36% and 0.19% for females and males, respectively. Age ranged from 66 to 85 years [mean 76.3 (SD 6.4)]. PPCNV were located nasal to disc in 41.7%, measuring 0.46–7.93 mm 2 [mean 2.81 mm 2 (SD 2.82)]. All PPCNV eyes had peripapillary RPE changes. One subject had no ARM, 1 angioid streaks, and 30% RPD. No direct foveal involvement, or reduced VA attributable to PPCNV was observed. Conclusion: PPCNV were infrequent in this population, more common in females, and often located nasal to the disc, without foveal extension. Peripapillary degenerative changes were universal, and strong association with ARM was observed in eyes with PPCNV. Typically, PPCNV were asymptomatic with VA preservation

An Optimized Roadside Units (RSU) Placement for Delay-Sensitive Applications in Vehicular Networks

International audienceOver the last few years, a lot of applications have been developed for Vehicular Ad Hoc NETworks (VANETs) to exchange information between vehicles. However, VANET is basically a Delay Tolerant Network (DTN) characterized by intermittent connectivity, long delays and message losses especially in low density regions [1]. Thus, VANET requires the use of an infrastructure such as Roadside Units (RSUs) that permits to enhance the network connectivity. Nevertheless, due to their deployment cost, RSUs need to be optimally deployed. Hence, the main objective of this work is to provide an optimized RSUs placement for delay-sensitive applications in vehicular networks that improves the end-to-end application delay and reduces the deployment cost. In this paper, we first mathematically model the placement problem as an optimization problem. Then, we propose our novel solution called ODEL. ODEL is a two-steps technique that places RSUs only in useful locations and allows both vehicle-to-vehicle and vehicle-to-infrastructure communication: (i) the first step is comprehensive study that looks for the RSUs candidates locations based on connectivity information, and (ii) the second step uses genetic algorithm and Dijkstra algorithm to reduce the number of RSUs based on the deliverance time requirement and the deployment cost. We show the effectiveness of our solution for different scenarios in terms of applications delay (reduced by up to 84%) and algorithm efficiency (computation performance reduced by up to 79% and deployment cost reduced at least by up to 23%)

Implementation of accounting information systems and information technology (IT) in the sustainability of the developed economic units

This paper focuses on the implementation of accounting information systems (AIS) and information technology (IT) in the sustainability of developed economic units. The objectives of this study are to characterize economic units, study the application of AIS, explain the effectiveness of AIS and IT on economic units, and investigate the role of IT specialists. To achieve these objectives, a comprehensive analysis is conducted to understand the nature, structure, and operations of developed economic units. The study explores how AIS are implemented and utilized within these units, examining the processes, procedures, and technologies involved in collecting, storing, processing, and reporting financial and non-financial data. Additionally, the impact and effectiveness of AIS and IT on the overall performance and sustainability of economic units are assessed, highlighting the benefits and challenges associated with their adoption and integration. The results obtained demonstrate the positive impact of effective AIS and IT implementation on economic unit performance, including improved decision-making capabilities, streamlined operations, and enhanced financial reporting. However, limitations such as sample size and data reliability should be acknowledged. To overcome these limitations, future research should consider larger and more diverse datasets, longitudinal studies, and the involvement of multiple stakeholders. In conclusion, this research provides valuable insights into the implementation of AIS and IT in developed economic units and highlights their significance in ensuring sustainability. The findings can inform decision-makers and practitioners in optimizing the utilization of AIS and I

Self-Organization Framework for Mobile Ad Hoc Networks

International audienceMobile ad hoc networks (MANETs) face a number of challenges, in particular due to dynamic network topology and large variable number of mobile nodes. To overcome these problems an effective solution is to define a self-organizing architecture that facilitates the network management task and permits to deploy wide panoply of services. One method to organize such networks is to define a virtual backbone that covers all the nodes in the network. In this paper we propose new self-organization architecture based on an optimized CDS construction. In this approach, the neighbors select CDS nodes intelligibly. In the selection processes, a new weight parameter depending on energy, link quality and connectivity is introduced in order to increase the CDS lifetime and hence the network performances. To study the benefits of this new architecture, we propose a new routing protocol called "PROC" (Proactive Routing based on Optimized CDS). Simulation results, using NS2, show that PROC minimizes the overhead and the energy consumption compared to the well-known OLSR routing protocol

Визначення втомної поведінки композитної однострунної конструкції на основі квазістатичного методу

In this investigation, the Mechanical Behavior of the composite Single-Stringer structure was subjected to numerical analysis in order to better understand its properties. As the primary material for the modeling process, the carbon-epoxy IM7/8552 with quasi-isotropic Layups has been utilized. The outcomes of the numerical analysis that were carried out on the structure while it was in its static state have been put into the structural tool that was developed by the ANSYS programme. The fundamental boundary conditions have been defined on the basis of the information that was received from the testing. Static forces with a combined magnitude of 13.7 kN are being applied to the composite Single-Stringer structure. Shear stresses, direction deformation, von mises stresses, and total deformation have all been shown to have an effect on a material's mechanical behaviour, and this effect has been demonstrated. The calculations indicate that there is a maximum amount of bending that can take place as a direct result of the load that is being applied, and that amount is equal to 0.0147. The maximum amount of bending that can take place as a direct result of the load that is being applied is equal to 0.0147. As a consequence of the application of 13.7 kN of pressure, the von Mises stress, which is also frequently referred to as comparable stresses, has reached 51.9 MPa. Shear stresses have been estimated in three distinct plans, and it was discovered that the shear stress that was applied to the XY plane achieved a maximum of 15 MPa, but the shear stress that was applied to the XZ plane reached a maximum of 9.8 MPa. This was found. Both aeroplanes were put through precisely the same amount of tension at the exact same time. At this time, the shear stress on the plane YZ has reached a level of 1.5 MPa.У цьому дослідженні механічна поведінка композитної однострунної конструкції була піддана числовому аналізу, щоб краще зрозуміти її властивості. Як основний матеріал для процесу моделювання використовувався вуглецевий епоксид IM7/8552 з квазіізотропними Layups. Результати числового аналізу, проведеного на конструкції, коли вона перебувала в статичному стані, були введені в структурний інструмент, розроблений програмою ANSYS. Фундаментальні граничні умови були визначені на основі інформації, отриманої від випробувань. Статичні сили із сумарною величиною 13,7 кН застосовуються до композитної однострунної конструкції. Доведено, що напруження зсуву, напрямна деформація, напруги фон Мізеса та повна деформація впливають на механічну поведінку матеріалу, і цей ефект було продемонстровано. Розрахунки показують, що існує максимальна величина вигину, яка може мати місце як прямий результат прикладеного навантаження, і ця величина дорівнює 0,0147. Внаслідок застосування тиску 13,7 кН напруга фон-Мізеса, яку також часто називають порівнянними напругами, досягла 51,9 МПа. Напруги зсуву були оцінені за трьома різними планами, і було виявлено, що напруга зсуву, прикладена до площини XY, досягла максимуму 15 МПа, але напруга зсуву, прикладена до площини XZ, досягла максимуму 9,8 МПа. У цей час напруга зсуву на площині YZ досягла рівня 1,5 МПа

A Stochastic Theoretical Game Approach for Resource Allocation in Vehicular Fog Computing

International audienceMobile devices have usually limited capabilities in terms of computation power, battery lifetime, storage size and available bandwidth. Thus, to address these limitations and to continue supporting the ever-increasing application requirements, service providers use powerful servers in order to offer services through the cloud. However, due to latency and QoS limitations, cloud computing still does not solve all the problems of newly emerging mobile applications demands. Thus, a more recent development is to push the storage and processing capabilities to the edge of access network closer to end users, which introduce the new concept of fog computing. Fog computing is a decentralized computation framework which essentially extends cloud computing resources and services to the edge of access network [2]