Mathematics, Statistics & Physics: Recent submissions
Now showing items 61-80 of 742
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Surface layer modification of ion bombarded HDPE
( Elsevier , 2004 , Article)Press-moulded, high density polyethylene (HDPE) samples were subjected to ion bombardment and effects of the modification studied. He+ ions of energy 100 keV or Ar+ ions of energy 130 keV were applied in the range of dose ... -
The effects of ion bombardment of ultra-high molecular weight polyethylene
( Elsevier , 2006 , Article)Ion bombardment is a suitable tool to improve tribological properties of polymers. In this study UHMWPE samples were bombarded with 130keV He ions to the fluences ranging from 1×1014 to 2×1016cm−2. RBS and NRA techniques ... -
Effectiveness of two and three doses of COVID-19 mRNA vaccines against infection, symptoms, and severity in the pre-omicron era: A time-dependent gradient
( Elsevier , 2024 , Article)BackgroundVaccines were developed and deployed to combat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This study aimed to characterize patterns in the protection provided by the BNT162b2 and ... -
Addressing bias in the definition of SARS-CoV-2 reinfection: implications for underestimation
( Frontiers Media , 2024 , Article)Introduction: Reinfections are increasingly becoming a feature in the epidemiology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, accurately defining reinfection poses methodological ... -
Prevalence of hepatitis B and C viruses among migrant workers in Qatar.
( Springer Nature , 2024 , Article)Limited data exist on viral hepatitis among migrant populations. This study investigated the prevalence of current hepatitis B virus (HBV) infection and lifetime hepatitis C virus (HCV) infection among Qatar's migrant craft ... -
The effect of graphene on the activation energy of grain growth for the nanocrystalline thermoelectric n-type Bi2Te2.7Se0.3
( Springer Nature , 2022 , Article)Even though bismuth telluride is frequently produced by mechanical alloying for thermoelectric materials, no data has been published addressing the thermal behavior and activation energy of the milled n-type Bi2Te2.7Se0.3 ... -
Synchronization and chimeras in a network of photosensitive FitzHugh-Nagumo neurons
( Springer Science and Business Media B.V. , 2021 , Article)Recently, a photosensitive model has been proposed that takes into account nonlinear encoding and responses of photosensitive neurons that are subject to optical signals. In the model, a photocell term has been added to ... -
Proposing a Nondestructive and Intelligent System for Simultaneous Determining Flow Regime and Void Fraction Percentage of Gas-Liquid Two Phase Flows Using Polychromatic X-Ray Transmission Spectra
( Springer , 2021 , Article)Two phase flows are of particular importance in various research fields. In the current article, a novel system consists of an X-ray tube and one sodium iodide crystal detector with ability of determining type of flow ... -
Application of artificial intelligence and gamma attenuation techniques for predicting gas-oil-water volume fraction in annular regime of three-phase flow independent of oil pipeline's scale layer
( MDPI AG , 2021 , Article)To the best knowledge of the authors, in former studies in the field of measuring volume fraction of gas, oil, and water components in a three-phase flow using gamma radiation technique, the existence of a scale layer has ... -
A image encryption algorithm based on chaotic Lorenz system and novel primitive polynomial S-boxes
( Springer , 2021 , Article)We have proposed a robust, secure and efficient image encryption algorithm based on chaotic maps and algebraic structure. Nowadays, the chaotic cryptosystems gained more attention due to their efficiency, the assurance of ... -
Cryptanalysis of nonlinear confusion component based encryption algorithm
( Elsevier , 2021 , Article)Recently many substitution box based encryption algorithms ensuring privacy have been proposed. Many, chaotic map based S-boxes have been generated posing high nonlinearity and strong cryptographic properties. Encryption ... -
Computational study of metal doped graphene nanoribbon as a potential platform for detection of H2S
( Elsevier Ltd , 2021 , Article)Theoretical investigation for detection of hydrogen sulfide (H2S) gas using hydrogen/nitrogen-terminated armchair graphene nanoribbon (HAGNR and NAGNR) doped with Pt is presented in this study. The investigation was ... -
First principle study of transition metals codoped MoS2 as a gas sensor for the detection of NO and NO2 gases
( Elsevier B.V. , 2021 , Article)Exposure to nitrogen oxides (NOx) has been reported to seriously affect the respiratory systems. More precisely, breathing NOx may lead to the appearance of asthma symptoms, and may also result in the infection with asthma ... -
Co-doped zigzag graphene nanoribbon based gas sensor for sensitive detection of H2S: DFT study
( Academic Press , 2021 , Article)In this work, we present a highly sensitive gas sensor for the detection of poisonous hydrogen sulfide gas (H2S) based on copper and zinc co-doped zigzag graphene nanoribbon (Cu/Zn-ZGNR). The electronic properties as well ... -
Sensitive SO2 gas sensor utilizing Pt-doped graphene nanoribbon: First principles investigation
( Elsevier Ltd , 2021 , Article)The objective of this work is to seek a highly sensitive gas sensor for the detection of sulfur dioxide (SO2) by investigating the impacts of passivation as well as metal doping of armchair-edge graphene nanoribbon (AGNR) ... -
Control of parabolic PDEs with time-varying spatial domain: Czochralski crystal growth process
( Taylor and Francis Ltd. , 2013 , Article)This paper considers the optimal control problem for a class of convection-diffusion-reaction systems modelled by partial differential equations (PDEs) defined on time-varying spatial domains. The class of PDEs is characterised ... -
Optimal control of an advection-dominated catalytic fixed-bed reactor with catalyst deactivation
( Elsevier , 2013 , Article)The paper focuses on the linear-quadratic control problem for a time-varying partial differential equation model of a catalytic fixed-bed reactor. The classical Riccati equation approach, for time-varying infinite-dimensional ... -
Infinite-dimensional LQ optimal control of a dimethyl ether (DME) catalytic distillation column
( Elsevier , 2012 , Article)This contribution addresses the development of a linear quadratic (LQ) regulator in order to control the concentration profiles along a catalytic distillation column, which is modelled by a set of coupled hyperbolic partial ... -
Boundary optimal (LQ) control of coupled hyperbolic PDEs and ODEs
( Elsevier , 2013 , Article)This contribution addresses the development of a linear quadratic (LQ) regulator for a set of hyperbolic PDEs coupled with a set of ODEs through the boundary. The approach is based on an infinite-dimensional Hilbert ... -
Boundary optimal control design for a system of parabolic-hyperbolic PDEs coupled with an ODE
( Taylor and Francis Ltd. , 2020 , Article)This paper deals with the design of a boundary optimal controller for a general model of parabolic-hyperbolic PDEs coupled with an ODE. The augmented infinite-dimensional state-space representation has been used in order ...
