73,951 research outputs found

    Passive Optical Network Dynamic Bandwidth Allocation Algorithms for Converged Fronthaul

    No full text
    The research presented in this thesis is focused on the use of passive optical network (PON) dynamic bandwidth allocation (DBA) algorithms for converged fronthaul. This work adapts and extends an existing model for use with a status reporting DBA that incorporates a colorless grant. This thesis also proposes a hybrid DBA that operates with the status reporting DBA and cooperative DBA. The models for the status reporting DBA and the proposed hybrid DBA are implemented in the OMNeT++ network simulator. The performance of both DBAs is evaluated using four simulation experiments in two deployment scenarios for a 10 Gbit/s symmetric PON (XGS-PON) system with an emphasis on the average optical network unit (ONU) upstream queueing delay and the proportion of frames meeting the latency requirement for fronthaul traffic. This is achieved by allocating bandwidth to the different types of traffic in a converged network based on their priority and latency requirement. The key findings from the simulation experiments show that, when the delay distribution of frames is analysed, a status reporting DBA that incorporates a colorless grant is suitable for meeting the latency requirement in a converged network, provided an adequate allocation of bandwidth is made available for fronthaul traffic. More than 99% of the fronthaul traffic at 80% traffic load in all scenarios meet the fronthaul latency requirement in the status reporting DBA. Furthermore, when the two DBAs are compared, the hybrid DBA provides zero frame loss for fronthaul traffic in all scenarios which is not achievable using the status reporting DBA

    ENHANCING STUDENT ENGAGEMENT, TEACHER SELF-EFFICACY, AND PRINCIPAL LEADERSHIP SKILLS THROUGH MORNING MEETING IN AN ONLINE LEARNING ENVIRONMENT

    Get PDF
    This study examined the experiences of educators in a small, rural elementary school who provided live instruction in an online setting during the COVID-19 pandemic. The scholarly practitioner collaborated with inquiry partners to enhance student engagement, teacher self-efficacy, and principal leadership skills by implementing Morning Meeting, a social and emotional learning program from Responsive Classroom®, when students participated in remote online learning. The scholarly practitioner used over four decades of research about efficacy and identified leadership strategies and approaches that assisted in building individual and collective teacher efficacy so that teachers could effectively engage students. Behavioral, emotional, and cognitive engagement were identified in research and used by teachers to determine the quality of participation in Morning Meeting. Teachers took daily and weekly attendance to measure engagement, and the scholarly practitioner facilitated team meetings with groups of teachers to compile comments and statements regarding student engagement. These statements were coded using pre-selected codes based on research about types of student engagement. The scholarly practitioner facilitated the administration of a pre-study and post-study Teacher Self-Efficacy Scale so that individual, grade-span, and full-school efficacy data could be compiled. In addition, the scholarly practitioner held team meetings with the teachers to compile comments and categorize those statements into four areas: job accomplishment, skill development, social interaction, and coping with job stress. These four areas were also coded using the four categories described on the Teacher Self-Efficacy Scale. The scholarly practitioner also maintained a journal using a self-reflection tool about the lived experiences before, during, and after the study. The emphasis on this journal was about the development and growth of leadership skills, and the categories were pre-coded using Bernard Bass’s categories of transformational leadership: individualized consideration, inspirational motivation, idealized influence, and intellectual stimulation. Student engagement increased throughout the study, and 77 percent of students were fully engaged during the study. Teachers expressed an increase in collective efficacy at the conclusion of the study, and six of the eight teachers reported individual increases in efficacy. The scholarly practitioner’s use of differentiation within the context of transformational leadership was observed most frequently in the study

    Reconfigurable Intelligent Surface Aided Cellular Networks With Device-to-Device Users

    Get PDF

    Traffic Generation using Containerization for Machine Learning

    Get PDF

    The MeerKAT Galaxy Cluster Legacy Survey: Survey overview and highlights

    Get PDF
    MeerKAT’s large number (64) of 13.5 m diameter antennas, spanning 8 km with a densely packed 1 km core, create a powerful instrument for wide-area surveys, with high sensitivity over a wide range of angular scales. The MeerKAT Galaxy Cluster Legacy Survey (MGCLS) is a programme of long-track MeerKAT L-band (900−1670 MHz) observations of 115 galaxy clusters, observed for ∼6−10 h each in full polarisation. The first legacy product data release (DR1), made available with this paper, includes the MeerKAT visibilities, basic image cubes at ∼8″ resolution, and enhanced spectral and polarisation image cubes at ∼8″ and 15″ resolutions. Typical sensitivities for the full-resolution MGCLS image products range from ∼3−5 μJy beam−1. The basic cubes are full-field and span 2° × 2°. The enhanced products consist of the inner 1.2° × 1.2° field of view, corrected for the primary beam. The survey is fully sensitive to structures up to ∼10′ scales, and the wide bandwidth allows spectral and Faraday rotation mapping. Relatively narrow frequency channels (209 kHz) are also used to provide H I mapping in windows of 0 < z < 0.09 and 0.19 < z < 0.48. In this paper, we provide an overview of the survey and the DR1 products, including caveats for usage. We present some initial results from the survey, both for their intrinsic scientific value and to highlight the capabilities for further exploration with these data. These include a primary-beam-corrected compact source catalogue of ∼626 000 sources for the full survey and an optical and infrared cross-matched catalogue for compact sources in the primary-beam-corrected areas of Abell 209 and Abell S295. We examine dust unbiased star-formation rates as a function of cluster-centric radius in Abell 209, extending out to 3.5 R 200. We find no dependence of the star-formation rate on distance from the cluster centre, and we observe a small excess of the radio-to-100 μm flux ratio towards the centre of Abell 209 that may reflect a ram pressure enhancement in the denser environment. We detect diffuse cluster radio emission in 62 of the surveyed systems and present a catalogue of the 99 diffuse cluster emission structures, of which 56 are new. These include mini-halos, halos, relics, and other diffuse structures for which no suitable characterisation currently exists. We highlight some of the radio galaxies that challenge current paradigms, such as trident-shaped structures, jets that remain well collimated far beyond their bending radius, and filamentary features linked to radio galaxies that likely illuminate magnetic flux tubes in the intracluster medium. We also present early results from the H I analysis of four clusters, which show a wide variety of H I mass distributions that reflect both sensitivity and intrinsic cluster effects, and the serendipitous discovery of a group in the foreground of Abell 3365

    Antisense locked nucleic acid gapmers to control Candida albicans filamentation

    Get PDF
    Whereas locked nucleic acid (LNA) has been extensively used to control gene expression, it has never been exploited to control Candida virulence genes. Thus, the main goal of this work was to compare the efficacy of five different LNA-based antisense oligonucleotides (ASO) with respect to the ability to control EFG1 gene expression, to modulate filamentation and to reduce C. albicans virulence. In vitro, all LNA-ASOs were able to significantly reduce C. albicans filamentation and to control EFG1 gene expression. Using the in vivo Galleria mellonella model, important differences among the five LNA-ASOs were revealed in terms of C. albicans virulence reduction. The inclusion of PS-linkage and palmitoyl-2-amino-LNA chemical modification in these five LNA gapmers proved to be the most promising combination, increasing the survival of G. mellonella by 40%. Our work confirms that LNA-ASOs are useful tools for research and therapeutic development in the candidiasis field.This study was supported by the Portuguese Foundation forScience and Technology (FCT) under the strategic funding of UIDB/04469/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European RegionalDevelopment Fund under the scope of Norte2020-ProgramaOperacional Regional do Norte and Daniela Eira Araújo [SFRH/BD/121417/2016] PhD grant. The authors also acknowledge theproject funding by the“02/SAICT/2017–Projetos de Investiga-ção Científica e Desenvolvimento Tecnológico (IC&DT)–POCI-01-0145-FEDER-028893”. VILLUM Fonden is acknowledgedfor funding the Biomolecular Nano-scale Engineering Center(BioNEC), a Villum center of excellence, grant numberVKR18333. Funding received by iBB-Institute for Bioengineer-ing and Biosciences from FCT (UID/BIO/04565/2020) andPrograma Operacional Regional de Lisboa 2020 (Project No.007317) is also acknowledged. We acknowledge Dr. LucíliaGoreti Pinto, Life and Health Sciences Research Institute(ICVS), School of Medicine, University of Minho, forprocessing and sectioningG. mellonellatissue samples.The authors declare no conflict of interest.info:eu-repo/semantics/publishedVersio

    EnTruVe: ENergy and TRUst-aware Virtual Machine Allocation in VEhicle Fog Computing for Catering Applications in 5G

    No full text
    It is undoubted that fog computing contributes in catering the latency-stringent applications of 5G, and one of the enabling technologies that fundamentally ensure the success of fog computing is virtualization as it offers isolation and platform independence. Although the emergence of vehicle-based fog (referred to as v-fog) facilities can certainly benefit from these desirable features of virtualization, there are several challenges that need to be addressed in order to realize the full potential that v-fogs can offer. One of the challenges of virtualization in v-fog is Virtual Machine (VM) migration. There are several factors that trigger a VM migration in a v-fog such as vehicle resource depletion. VM migrations would not only lead to nonessential usage of valuable resources (e.g. energy, bandwidth, memory) in the v-fogs, but also incur various overheads and performance degradation throughout the whole network. Thus, minimizing VM migrations is necessary. Furthermore, to ensure the seamless VM migrations between v-fogs, trust of v-fogs is required. While there exists studies of trust in the virtualization of cloud, they are irrelevant to v-fogs as v-fogs are different in nature (i.e. heterogeneous, mobile) from the cloud. Additionally, trust is not included in the decision making mechanisms of VM allocation for vehicular environments in the existing works. Moreover, as vehicle resources are constrained, their energy has to be utilized efficiently. In this paper, we propose EnTruVe, an ENergy and TRUst-aware VM allocation in VEhicle fog computing solution that aims to minimize the number of VM migration while reducing VM processing associated energy consumption as much as possible. The VM allocation algorithm in EnTruVe provides a larger selection pool of v-fogs that meets the VMs requirements (e.g. trust, latency), thereby ensuring higher chances of success of VM allocation. Using Analytic Hierarchy Process (AHP), the proposed EnTruVe solution evaluates the v-fogs based on a set of metrics (e.g. energy consumption, end-to-end latency) to select the optimal v-fog for a VM allocation. Results obtained demonstrate that EnTruVe has the least number of VM migrations and it is the most energy efficient solution. Additionally, it shows that EnTruVe provides the highest utilization of v-fogs of up to 57.6% in comparison to other solutions as the number of incoming requests increases

    Underwater optical wireless communications in turbulent conditions: from simulation to experimentation

    Get PDF
    Underwater optical wireless communication (UOWC) is a technology that aims to apply high speed optical wireless communication (OWC) techniques to the underwater channel. UOWC has the potential to provide high speed links over relatively short distances as part of a hybrid underwater network, along with radio frequency (RF) and underwater acoustic communications (UAC) technologies. However, there are some difficulties involved in developing a reliable UOWC link, namely, the complexity of the channel. The main focus throughout this thesis is to develop a greater understanding of the effects of the UOWC channel, especially underwater turbulence. This understanding is developed from basic theory through to simulation and experimental studies in order to gain a holistic understanding of turbulence in the UOWC channel. This thesis first presents a method of modelling optical underwater turbulence through simulation that allows it to be examined in conjunction with absorption and scattering. In a stationary channel, this turbulence induced scattering is shown to cause and increase both spatial and temporal spreading at the receiver plane. It is also demonstrated using the technique presented that the relative impact of turbulence on a received signal is lower in a highly scattering channel, showing an in-built resilience of these channels. Received intensity distributions are presented confirming that fluctuations in received power from this method follow the commonly used Log-Normal fading model. The impact of turbulence - as measured using this new modelling framework - on link performance, in terms of maximum achievable data rate and bit error rate is equally investigated. Following that, experimental studies comparing both the relative impact of turbulence induced scattering on coherent and non-coherent light propagating through water and the relative impact of turbulence in different water conditions are presented. It is shown that the scintillation index increases with increasing temperature inhomogeneity in the underwater channel. These results indicate that a light beam from a non-coherent source has a greater resilience to temperature inhomogeneity induced turbulence effect in an underwater channel. These results will help researchers in simulating realistic channel conditions when modelling a light emitting diode (LED) based intensity modulation with direct detection (IM/DD) UOWC link. Finally, a comparison of different modulation schemes in still and turbulent water conditions is presented. Using an underwater channel emulator, it is shown that pulse position modulation (PPM) and subcarrier intensity modulation (SIM) have an inherent resilience to turbulence induced fading with SIM achieving higher data rates under all conditions. The signal processing technique termed pair-wise coding (PWC) is applied to SIM in underwater optical wireless communications for the first time. The performance of PWC is compared with the, state-of-the-art, bit and power loading optimisation algorithm. Using PWC, a maximum data rate of 5.2 Gbps is achieved in still water conditions
    corecore