Mathematics, Statistics & Physics: Recent submissions
Now showing items 301-320 of 740
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An LP model for optimizing a supply chain management system for steel company
( Newswood Limited , 2014 , Conference Paper)In this research, we have developed a linear programming formulation to describe Qatar steel manufacturing supply chain from suppliers to consumers. The purpose of the model is to provide answers regarding the optimal ... -
Long-term COVID-19 booster effectiveness by infection history and clinical vulnerability and immune imprinting: a retrospective population-based cohort study
( Elsevier , 2023 , Article)BackgroundLong-term effectiveness of COVID-19 mRNA boosters in populations with different previous infection histories and clinical vulnerability profiles is inadequately understood. We aimed to investigate the effectiveness ... -
BNT162b2 antigen dose and SARS-CoV-2 omicron infection in adolescents
( Elsevier , 2023 , Other)COVID-19 vaccine antigen dose might affect protection against SARS-CoV-2 infection,1, 2 but direct evidence to quantify this effect is absent. We conducted a matched, retrospective, cohort study using a regression ... -
The general solution for the relativistic and nonrelativistic Schrödinger equation for the δ(n) -function potential in 1-dimension using cutoff regularization, and the fate of universality
( World Scientific Publishing , 2022 , Article)A general method has been developed to solve the Schrödinger equation for an arbitrary derivative of the δ-function potential in 1-d using cutoff regularization. The work treats both the relativistic and nonrelativistic ... -
Assessing the Impact of Major Political and Institutional Factors on New Businesses: The Case of Qatar
( Springer , 2022 , Book chapter)This chapter provides an assessment of the impact of the major political and institutional factors on establishing new businesses in the State of Qatar in the long run using the autoregressive distributed lag (ARDL) model. ... -
The relevance of supply side taxation for attracting foreign direct investment to developing countries: evidence from Egypt
( University of New South Wales , 2021 , Article)Many developing countries commonly use tax incentives as a key instrument for attracting foreign direct investment (FDI). Empirical studies have identified a causal relationship between FDI and a number of determinants ... -
A review on lithium recovery using electrochemical capturing systems
( Elsevier , 2021 , Article Review)Resource recovery from natural reserves is appealing and Li extraction from different brines is in the forefront. Li extraction by membranes is reviewed in the literature much more than electrochemical processes. However, ... -
Pt-Based Nanostructures for Electrochemical Oxidation of CO: Unveiling the Effect of Shapes and Electrolytes
( MDPI , 2022 , Article)Direct alcohol fuel cells are deemed as green and sustainable energy resources; however, CO-poisoning of Pt-based catalysts is a critical barrier to their commercialization. Thus, investigation of the electrochemical CO ... -
Rectangular eigenvalue problems
( Springer , 2022 , Article)Often the easiest way to discretize an ordinary or partial differential equation is by a rectangular numerical method, in which n basis functions are sampled at m ≫ n collocation points. We show how eigenvalue problems can ... -
Protection from previous natural infection compared with mRNA vaccination against SARS-CoV-2 infection and severe COVID-19 in Qatar: a retrospective cohort study
( Elsevier , 2022 , Article)BackgroundUnderstanding protection conferred by natural SARS-CoV-2 infection versus COVID-19 vaccination is important for informing vaccine mandate decisions. We compared protection conferred by natural infection versus ... -
Heat Transfer Attributes of Gold–Silver–Blood Hybrid Nanomaterial Flow in an EMHD Peristaltic Channel with Activation Energy
( MDPI , 2022 , Article)The heat enhancement in hybrid nanofluid flow through the peristaltic mechanism has received great attention due to its occurrence in many engineering and biomedical systems, such as flow through canals, the cavity flow ... -
Effect of Magnetic Baffles and Magnetic Nanofluid on Thermo-Hydraulic Characteristics of Dimple Mini Channel for Thermal Energy Applications
( MDPI , 2022 , Article)The combined effect of a magnetic baffle and a dimple turbulator on the heat transfer and pressure drop is investigated computationally in a mini channel. Fe3O4 magnetic nanofluid is used as a working fluid. The Reynolds ... -
Siting of pv power plants on inclined terrains
( Taylor and Francis Ltd. , 2014 , Article)Most of the studies conducted on solar energy assessment and solar system siting focus on flat terrains that are usually difficult and expensive to acquire in urban areas. This paper investigates the possibility of using ... -
Closed form solution of nonlinear oscillation of a cantilever beam using λ-symmetry linearization criteria
( Elsevier , 2022 , Article)A mechanical system, in general, undergoes vibrational motion when the system is subjected to a tension or an external force. One of the examples of such a system is a cantilever beam when it is exposed to a bending action. ... -
Performance enhancement of CZTS-based solar cells with tungsten disulfide as a new buffer layer
( Elsevier , 2023 , Article)2D layered Transition Metal Dichalcogenide materials (TMDCs) have shown promising potential for ultra-thin photovoltaic and solar cells applications owing to their outstanding photon absorption and electrical and optoelectronics ... -
Covid-19 Vaccine Protection among Children and Adolescents in Qatar.
( Massachusetts Medical Society , 2022 , Article)The BNT162b2 vaccine against coronavirus disease 2019 (Covid-19) has been authorized for use in children 5 to 11 years of age and adolescents 12 to 17 years of age but in different antigen doses. We assessed the real-world ... -
Duration of immune protection of SARS-CoV-2 natural infection against reinfection.
( Oxford University Press , 2022 , Article)The future of the SARS-CoV-2 pandemic hinges on virus evolution and duration of immune protection of natural infection against reinfection. We investigated duration of protection afforded by natural infection, the effect ... -
Effects of SARS-CoV-2 Alpha, Beta, and Delta variants, age, vaccination, and prior infection on infectiousness of SARS-CoV-2 infections
( Frontiers Media , 2022 , Article)In 2021, Qatar experienced considerable incidence of SARS-CoV-2 infection that was dominated sequentially by the Alpha, Beta, and Delta variants. Using the cycle threshold (Ct) value of an RT-qPCR-positive test to proxy ... -
A Note on a Class of Generalized Parabolic Marcinkiewicz Integrals along Surfaces of Revolution
( MDPI , 2022 , Article)In this article, certain sharp Lp estimates for a specific class of generalized Marcinkiewicz operators with mixed homogeneity associated to surfaces of revolution are established. By virtue of Yano’s extrapolation ... -
Least-squares spectral methods for ODE eigenvalue problems
( Society for Industrial and Applied Mathematics , 2022 , Article)We develop spectral methods for ODEs and operator eigenvalue problems that are based on a least-squares formulation of the problem. The key tool is a method for rectangular generalized eigenvalue problems, which we extend ...
