Applied Sciences

Permanent URI for this collection

https://repository.nrf.go.ke/handle/123456789/1485

Browse

Browsing Applied Sciences by Funder "NRF"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    CERTAIN INEQUALITIES FOR (a,B)- NORMAL TRANSLOID OPERATORS ON HILBERT SPACES
    (International Journal of Academic Studies, 2015-11-29) Nyaluke Kiprono Wesley” , N. B. Okelo , Omolo Ongati-
    Let H be an infinite dimensional complex Hilbert space and N.(H) denote the class of (a, 2)-normal transaloid operators. In this paper, we characterize (a, B)- normal transaloid operators and later determine norm and numerical radii inequalities for (a, 2)-normal transaloid operators.
  • Thumbnail Image
    Item
    CHANNEL STRUCTURED METAMATERIALS FOR SUPER RESOLUTION IMAGING
    (ASME, 2019-07-14) ohn Birir1, Michael J. Gatari and Prabhu Rajagopal
    ABSTRACT When inspection is required to be conducted from a remote distance, due for example to safety concerns, guided ultrasonic wave testing technique is the preferred choice. Guided waves are usually low frequency hence are not subjected to much attenuation relative to the bulk waves. As a result, guided waves can travel a longer distance. One of the limitations of guided waves however, is that the low frequency (longer wavelength) used lead to lower resolution capabilities due to the inherent diffraction limits of λ/2 (where λ is wavelength). Guided waves are therefore generally used as screening tools to locate areas of interest. A higher resolution technique is then employed to further investigate and characterize the features of defects in the identified areas. To overcome this challenge of resolution, a technique is proposed that increases the resolution capability of guided waves beyond the diffraction limit. Simulation using commercial finite element software is used to optimize variables involved in the proposed method. The simulation is then validated with experiments. In the present work a resolution of λ/72 is demonstrated experimentally.
  • Thumbnail Image
    Item
    Endophytic and epiphytic metabarcoding reveals fungal communities on cashew phyllosphere in Kenya
    (PLUS ONE, 2024-06-17) Dennis Wamalabe Mukhebi , Colletah Rhoda Musangi , Everlyne Moraa Isoe , Johnstone Omukhulu Neondo , Wilton Mwema Mbinda
    Plants intimately coexist with diverse taxonomically structured microbial communities that influence host health and productivity. The coexistence of plant microbes in the phyllosphere benefits biodiversity maintenance, ecosystem function, and community stability. However, differences in community composition and network structures of phyllosphere epiphytic and endophytic fungi are widely unknown. Using Illumina Miseq sequencing of internal transcribed spacer (ITS) and 28S rRNA gene amplicons, we characterised the epiphytic and endophytic fungal communities associated with cashew phyllosphere (leaf, flower and fruit) from Kwale, Kilifi and Lamu counties in Kenya. The ITS and 28S rRNA gene sequences were clustered into 267 and 108 operational taxonomic units (OTUs) at 97% sequence similarity for both the epiphytes and endophytes. Phylum Ascomycota was abundant followed by Basidiomycota, while class Saccharomycetes was most dominant followed by Dothideomycetes. The major non-ascomycete fungi were associated only with class Tremellales. The fungal communities detected had notable ecological functions as saprotrophs and pathotrophs in class Saccharomyectes and Dothideomycetes. The community composition of epiphytic and endophytic fungi significantly differed between the phyllosphere organs which was statistically confirmed by the Analysis of Similarity test (ANOSIM Statistic R: 0.3273, for 28S rRNA gene and ANOSIM Statistic R: 0.3034 for ITS). The network analysis revealed that epiphytic and endophytic structures were more specialized, modular and had less connectance. Our results comprehensively describe the phyllosphere cashewassociated fungal community and serve as a foundation for understanding the host-specific microbial community structures among cashew trees.
  • Thumbnail Image
    Item
    Simulation of Trust-Based Mechanism for Enhancing User Confidence in Mobile Crowdsensing Systems WHERE DO YOU CLASS THIS
    (IEEE ACCESS, 2020-01-31) DOROTHY MWONGELI KALUI, DEZHENG ZHANG, GEOFFREY MUCHIRI MUKETHA, AND JARED OKOYO ONSOMU
    With the rapid development of mobile technology and subsequent mass adoption of mobile devices, mobile crowdsensing (MCS) has gained a lot of research attention. In MCS systems, trust is a key focus in the overall improvement in the participant uptake of the sensing tasks. The trust-based scheme of MCS is studied to predict the damage level, the scores of quality-of-service (QoS), and the levels of qualityof-data (QoD) of MCS systems. Users can participate in MCS sensing based on trustworthy indicators that are related to user experience and system reputation, as well as the knowledge obtained about the MCS systems. This paper illustrates the establishment of user confidence during recruitment in MCS as it is very critical for the success of MCS systems and proposes a simulation trust-based mechanism (SiTBaM) approach. The level of MCS security is enhanced to protect the privacy of participants, so that participants can be assured that the MCS system they are working with during sensing moment is trustworthy. The application of SiTBaM in MCS is verified to yield better results as the simulations show that it offers higher QoS levels, QoD scores, as well as low damage levels in the presence of any task or many malicious users. These results were validated through comparisons with other schemes.