The Underwater Communication Link(UCL)is a crucial component of Underwater Wireless Optical Communication(UWOC)systems,requiring optimised design to mitigate the high power attenuation inherent in seawater.To ensure t...The Underwater Communication Link(UCL)is a crucial component of Underwater Wireless Optical Communication(UWOC)systems,requiring optimised design to mitigate the high power attenuation inherent in seawater.To ensure the reliability of an optimal UCL design,it is essential to account for the three primary scattering regimes:forward scattering(FSC),backward scattering(BSC),and isotropic scattering(ISC)in seawater channels.This study introduces a new photon-tracking model based on a discrete equation,facilitating Monte Carlo Simulation(MCS)to evaluate how different scattering regimes influence received photon distribution.Three distinct Scattering Regime Contribution Weight(SRCW)probability sets were employed,each representing different UCL operational configurations dominated by specific scattering regimes.The proposed modeling approach enables a comprehensive assessment of the temporal characteristics of received optical pulses,channel loss,and time spread-ultimately defining the optimal UCL design parameters.The key findings of this study include:(1)Enhancing the FSC regime dominance leads to a quasi-light waveguide effect over link spans and small Fields of View(FOV)<25°,significantly improving channel performance in Harbor seawater compared to Coastal seawater.(2)A well-designed UCL with a small FOV(<25°)can minimise channel loss and time spread,ensuring high capacity and efficient performance in both Coastal and Harbor seawaters.(3)When BSC and ISC contributions exceed FSC dominance,the received optical pulse undergoes significant temporal broadening,particularly for larger FOV angles(>25°)and extended link spans.(4)The developed novel MCS-based discrete equation provides a simple yet robust model for simulating photon propagation in both homogeneous and inhomogeneous underwater channels.These insights contribute to developing more efficient and reliable UCL designs with military standards by enhancing UWOC system performance over a longer linkspan for a given limited optical power across various underwater environments.展开更多
In this paper,the dust particle surface potential for argon-helium plasma is evaluated analytically and numerically in the context of negatively charged dust particles by employing a power-law(r,q)-distribution functi...In this paper,the dust particle surface potential for argon-helium plasma is evaluated analytically and numerically in the context of negatively charged dust particles by employing a power-law(r,q)-distribution function.Recent studies have reported the argon-helium plasma and conducted a brief theoretical and experimental survey.To deepen our understanding further,this study aims to analyze the argon-helium plasma comprehensively using the same pattern but with the(r,q)-distribution function.For this purpose,the current balance equations are derived for electron,helium and argon ions,when these charge species attain the quasineutrality condition.We numerically examined the currents of plasma species for a broad range of effective distribution function parameters r and q.It is revealed that the surface potential of dust particles is significantly affected by the parameters r and q,helium ion-to-electron temperature ratio,argon ion-to-electron temperature ratio,and helium ion to argon ion number density ratio.By incorporating the multi-ion(argon-helium)species,the significance of low-temperature nonMaxwellian dusty(complex)plasma is briefly examined.展开更多
Plasma X-ray sources for biological microscopy have been produced by focusing single shots from Nd:glass laser onto carbon rod targets at irradiances between 1 × 1013 W⋅cm−2 and 3 × 1013 W...Plasma X-ray sources for biological microscopy have been produced by focusing single shots from Nd:glass laser onto carbon rod targets at irradiances between 1 × 1013 W⋅cm−2 and 3 × 1013 W⋅cm−2 to expose test objects. The optimum parameters needed for obtaining high accurate information on the samples under test namely: the minimum energies and irradiances at a range of angles between the incoming laser beam and the normal to the resist, the depth of exposure of the photoresist as a function of incident laser energy (and irradiance) were concluded in this work.展开更多
Defect engineering in photocatalytic materials has garnered significant interest due to the considerable impact of defects on light absorption,charge separation,and surface reaction dynamics.However,a limited understa...Defect engineering in photocatalytic materials has garnered significant interest due to the considerable impact of defects on light absorption,charge separation,and surface reaction dynamics.However,a limited understanding of how these defects influence photocatalytic properties remains a persistent challenge.This review comprehensively analyzes the vital role of defect engineering for enhancing the photocatalytic performance,highlighting its significant influence on material properties and efficiency.It systematically classifies defect types,including vacancy defects(oxygen and metal vacancies),doping defects(anion and cation),interstitial defects,surface defects(step edges,terraces,kinks,and disordered layers),antisite defects,and interfacial defects in the core–shell structures and heterostructure borders.The impact of complex defect groups and manifold defects on improved photocatalytic performance is also examined.The review emphasizes the principal benefits of defect engineering,including the enhancement of light adsorption,reduction of band gaps,improved charge separation and movements,and suppression of charge recombination.These enhancements lead to a boost in catalytic active sites,optimization of electronic structures,tailored band alignments,and the development of mid-gap states,leading to improved structural stability,photocorrosion resistance,and better reaction selectivity.Furthermore,the most recent improvements,such as oxygen vacancies,nitrogen and sulfur doping,surface defect engineering,and innovations in heterostructures,defect-rich metal–organic frameworks,and defective nanostructures,are examined comprehensively.This study offers essential insights into modern techniques and approaches in defect engineering,highlighting its significance in addressing challenges in photocatalytic materials and promoting the advancement of effective and adaptable platforms for renewable energy and environmental uses.展开更多
基金The Deanship of Scientific Research(DSR)at King Abdulaziz University(KAU),Jeddah,Saudi Arabia,has funded this project under Grant No.(KEP-PhD:72-130-1443).
文摘The Underwater Communication Link(UCL)is a crucial component of Underwater Wireless Optical Communication(UWOC)systems,requiring optimised design to mitigate the high power attenuation inherent in seawater.To ensure the reliability of an optimal UCL design,it is essential to account for the three primary scattering regimes:forward scattering(FSC),backward scattering(BSC),and isotropic scattering(ISC)in seawater channels.This study introduces a new photon-tracking model based on a discrete equation,facilitating Monte Carlo Simulation(MCS)to evaluate how different scattering regimes influence received photon distribution.Three distinct Scattering Regime Contribution Weight(SRCW)probability sets were employed,each representing different UCL operational configurations dominated by specific scattering regimes.The proposed modeling approach enables a comprehensive assessment of the temporal characteristics of received optical pulses,channel loss,and time spread-ultimately defining the optimal UCL design parameters.The key findings of this study include:(1)Enhancing the FSC regime dominance leads to a quasi-light waveguide effect over link spans and small Fields of View(FOV)<25°,significantly improving channel performance in Harbor seawater compared to Coastal seawater.(2)A well-designed UCL with a small FOV(<25°)can minimise channel loss and time spread,ensuring high capacity and efficient performance in both Coastal and Harbor seawaters.(3)When BSC and ISC contributions exceed FSC dominance,the received optical pulse undergoes significant temporal broadening,particularly for larger FOV angles(>25°)and extended link spans.(4)The developed novel MCS-based discrete equation provides a simple yet robust model for simulating photon propagation in both homogeneous and inhomogeneous underwater channels.These insights contribute to developing more efficient and reliable UCL designs with military standards by enhancing UWOC system performance over a longer linkspan for a given limited optical power across various underwater environments.
文摘In this paper,the dust particle surface potential for argon-helium plasma is evaluated analytically and numerically in the context of negatively charged dust particles by employing a power-law(r,q)-distribution function.Recent studies have reported the argon-helium plasma and conducted a brief theoretical and experimental survey.To deepen our understanding further,this study aims to analyze the argon-helium plasma comprehensively using the same pattern but with the(r,q)-distribution function.For this purpose,the current balance equations are derived for electron,helium and argon ions,when these charge species attain the quasineutrality condition.We numerically examined the currents of plasma species for a broad range of effective distribution function parameters r and q.It is revealed that the surface potential of dust particles is significantly affected by the parameters r and q,helium ion-to-electron temperature ratio,argon ion-to-electron temperature ratio,and helium ion to argon ion number density ratio.By incorporating the multi-ion(argon-helium)species,the significance of low-temperature nonMaxwellian dusty(complex)plasma is briefly examined.
文摘Plasma X-ray sources for biological microscopy have been produced by focusing single shots from Nd:glass laser onto carbon rod targets at irradiances between 1 × 1013 W⋅cm−2 and 3 × 1013 W⋅cm−2 to expose test objects. The optimum parameters needed for obtaining high accurate information on the samples under test namely: the minimum energies and irradiances at a range of angles between the incoming laser beam and the normal to the resist, the depth of exposure of the photoresist as a function of incident laser energy (and irradiance) were concluded in this work.
基金Deanship of Research and Graduate Studies at King Khalid University,Grant/Award Number:RGP2/363/46。
文摘Defect engineering in photocatalytic materials has garnered significant interest due to the considerable impact of defects on light absorption,charge separation,and surface reaction dynamics.However,a limited understanding of how these defects influence photocatalytic properties remains a persistent challenge.This review comprehensively analyzes the vital role of defect engineering for enhancing the photocatalytic performance,highlighting its significant influence on material properties and efficiency.It systematically classifies defect types,including vacancy defects(oxygen and metal vacancies),doping defects(anion and cation),interstitial defects,surface defects(step edges,terraces,kinks,and disordered layers),antisite defects,and interfacial defects in the core–shell structures and heterostructure borders.The impact of complex defect groups and manifold defects on improved photocatalytic performance is also examined.The review emphasizes the principal benefits of defect engineering,including the enhancement of light adsorption,reduction of band gaps,improved charge separation and movements,and suppression of charge recombination.These enhancements lead to a boost in catalytic active sites,optimization of electronic structures,tailored band alignments,and the development of mid-gap states,leading to improved structural stability,photocorrosion resistance,and better reaction selectivity.Furthermore,the most recent improvements,such as oxygen vacancies,nitrogen and sulfur doping,surface defect engineering,and innovations in heterostructures,defect-rich metal–organic frameworks,and defective nanostructures,are examined comprehensively.This study offers essential insights into modern techniques and approaches in defect engineering,highlighting its significance in addressing challenges in photocatalytic materials and promoting the advancement of effective and adaptable platforms for renewable energy and environmental uses.
