91 research outputs found
Authentication Solutions in Industrial Internet of Things: A Survey
With the rapid growth of industry 4.0, the Industrial Internet of Things (IIoT) is considered to be a promising solution for converting normal operations to ‘smart’ operations in industrial sectors and systems. The well-known characteristics of IIoT has greatly improved the productivity and quality of many industrial sectors. IIoT allows the connectivity of many industrial smart devices such as, sensors, actuators and gateways. The connectivity feature makes this critical environment vulnerable to various cybersecurity attacks. Subsequently, maintaining the security of IIoT sys-tems remains a challenge to ensure their success. In particular, authenticating the connected IIoT devices is a must to ensure that they can be trusted and prevent any malicious attempts. Hence, the objective of this survey is to overview, discuss and analyze the different solutions related to de-vice authentication in the domain of IIoT. Also, we analyze the IIoT environment in terms of characteristics, architecture and security requirements. Similarly, we highlight the role of (machine-to-machine) M2M communication in IIoT. We further contribute to this survey by outlining several open issues that must be considered when designing authentication schemes for IIoT. Fi-nally, we highlight a number of research directions and open challenges
Graphene-like optical light field and its interaction with two-level atoms
The theoretical basis leading to the creation of a light field with a hexagonal honeycomb structure resembling graphene is considered along with its experimental realization and its interaction with atoms. It is argued that associated with such a light field is an optical dipole potential which leads to the diffraction of the atoms, but the details depend on whether the transverse spread of the atomic wave packet is larger than the transverse dimensions of the optical lattice (resonant Kapitza-Dirac effect) or smaller (optical Stern-Gerlach effect). Another effect in this context involves the creation of gauge fields due to the Berry phase acquired by the atom moving in the light field. The experimental realization of the light field with a honeycomb hexagonal structure is described using holographic methods and we proceed to explore the atom diffraction in the Kapitza-Dirac regime as well as the optical Stern-Gerlach regime, leading to momentum distributions with characteristic but different hexagonal structures. The artificial gauge fields too are shown to have the same hexagonal spatial structure and their magnitude can be significantly large. The effects are discussed with reference to typical parameters for the atoms and the fields
Development and performance characterisation of high concentrating multi-junction PV/Thermal technology
Multi-Junction (MJ) solar cells are new generation of Photovoltaic (PV) technology with high efficiency, better response to high solar concentration and lower temperature coefficients. MJ cells are integrated with high concentrating optical systems to maximise their power output. However, high concentration of solar radiation can lead to significant increase in the cells temperature thus cooling is essential which offers potential for heat recovery leading to the development of High Concentrator PV/Thermal (HCPV/T) systems. This thesis presents a detailed investigation of the MJ based HCPV/T optical, electrical and thermal performance.
The performance analysis of HCPV/T integrating
0.25x0.25 m Fresnel lens under concentration ratios of 425X (X=1000 W/m) was carried out to estimate the maximum power output that can be collected. It was found that the yearly total power yield can be up to 191.25 kWh. Therefore, 184 units of HCPV/T, which occupy only 11.5 m, can generate 35,190 kWh. Also, in comparison to the flat plate Silicon PV module with electrical efficiency of 20% and 1.2x0.8 m area, HCPV/T system can save about 76% of the area needed to meet this demand. On the other hand, in terms of pollution these units can displace about 23 tons of CO every year
Effect of Three Medicinal Plants Extracts on the Growth of Some Yeasts
This study conducted to detect the effect of the ethanolic extracts for some medicinal plants on 16 yeast species isolated from the oral cavity of cancer patients, three plants which are Lavandula angustifolia, Salvia officinalis and Syzygium aromaticum were used to study their inhibition bioactivity and compare their effect with three antifungal drugs (Fluconazole, Ketoconazole and Nystatin), the results showed that Ethanolic extract of L. angustifolia exhibited antifungal bioactivity against all yeast species and revealed inhibition zones ranged from 16-36 mm. with highest effect on C. parapsilosis whereas the lowest effect was on species H. uvarum, while the ethanolic extract of S. officinalis and S. aromaticum showed inhibition zones 16-27 mm. and 17-31 mm. respectively, the results showed that the plants extracts having much more effect on the yeasts growth from the antifungal drugs. Keywords: yeasts, medicinal plants, Ethanolic extracts
Isolation and Identification of Candida Species from the Oral Cavity of Cancer Patients Undergoing Chemotherapy in Basrah, Iraq
Candida species are a common normal flora in the human oral cavity , they can cause oral candidiasis especially in the immunocompromised patients like cancer patients. A total of 500 cancer patients and 200 healthy controls were included in this study. Breast cancer was the most prevalence between patients (145 cases) , followed by leukemia (114 cases) . Candida albicans was the most yeast species isolated from the oral cavity of the patients and control persons , followed by C. tropicalis and C. glabrata along with other non-Candida albicans Candida (NCAC).All the yeast isolates were identified by different phenotypic methods including germ tube and chlamydospores production, growing on chromogenic media and assimilation test. Keywords: Yeast, oral cavity, cancer patients, Candida specie
Performance of multi junction photovoltaic cells with high concentration ratio
AbstractConcentrating solar radiation on Photovoltaic (PV) has the potential to replace the expensive PV material with cheaper optical elements which also enhance the overall electrical output. The use of high solar concentration ratios with the triple junction III-V solar cells offers potential of high solar cell efficiency and power output. However, using high concentration ratios will increase the solar cell surface temperature which is inversely proportional to the PV electrical efficiency. This work investigates the effect of active cooling on the performance of triple junction PV cells with high solar concentration (up to 500X) in the harsh environment of Saudi Arabia where ambient temperatures can reach to 50o C in summer time, but with good clearance index of 0.6 and high yearly solar radiation of up to 2200 kWh/m2. Simulation results showed that as the concentration ratio increases, the effect of cooling on the PV efficiency increases
PCM examine of Silica/Decane nanostructure in the presence of copper oxide nanoparticles to improve the solar energy capacity of glass in the solar collectors via MD approach
Energy storage is of particular importance for the use of alternative energy sources. One of the new and efficient
procedures in thermal energy storage (TES) in the appropriate form is using phase change materials (PCM). PCMs
store energy in the latent heat (LH) of melting without mechanical tools, entirely intelligently, or anything other
than their intrinsic propensity to spontaneously change phases, adapt to environmental changes, and actively
seek for ways to use less energy. Because of the role of melting and freezing processes in TES systems, it is
significant to study and identify the behavior of PCMs during the melting and freezing process. In this investigation,
molecular dynamics simulation (MDS) has investigated the thermal behavior (TB) of glass in the presence
of paraffin (Decane) and CuO nanoparticles (NPs). The effect of the number of NPs with values of 1, 2, and 3 on
TB has been investigated. The results showes that in the absence of CuO NPs, the heat flux (HF) of the structure
converges to 678.168 W/m2. Then with the addition of 3 CuO NPs, the HF increased from 678.168 to 1506.23
W/m2. Also, the thermal conductivity (TC) of the structure in the final step is equal to 0.741 W/m.K, which
indicates the optimal behavior of the designed atomic structure. And by increasing the number of NPs to 3 NPs,
the TC increases to 1.48 W/m.K
Revisiting User Satisfaction and Intention to Use: A Cross-Sectional Study of e-Learning during Lockdown
Covid-19 related lockdowns forced students of higher education to receive education entirely online as a replacement for physical attendance in classrooms. This new situation caused students to discover the advantages and disadvantages of e-Learning and influenced their satisfaction and intention to use it. Consequently, this study revisits the intention to use and satisfaction-related theories based on pre-covid conditions. This revisit was necessary because the evidence suggests that students’ new situation has changed some determinants related to their satisfaction and intention to use. This situation warranted the simultaneous consideration of many dimensions when measuring user satisfaction and intention to use during the lockdown. This cross-sectional study developed an integrated model to measure students’ satisfaction and its impact on e-Learning intention to use. Structural equation modelling was used to conduct the empirical analysis. Nine hundred respondents from Malaysia and Saudi Arabia participated in this study. Students from Malaysia and Saudi Arabia showed marginal differences in their perceptions of e-Learning. The findings showed changes in students’ perceptions towards satisfaction and intention to use e-Learning, which might be due to using e-Learning exclusively
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