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Wyszukujesz frazę "Ahmed, N." wg kryterium: Autor

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    Wyświetlanie 1-44 z 44
    Tytuł:
    Measure valued solutions for systems governed by neutral differential equations on Banach spaces and their optimal control
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729292.pdf
    Data publikacji:
    2013
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    neutral differential equations
    Banach spaces
    optimal control
    Opis:
    In this paper we consider the question of existence of measure valued solutions for neutral differential equations on Banach spaces when there is no mild solutions. We prove the existence of measure solutions and their regularity properties. We consider also control problems of such systems and prove existence of optimal feedback controls for some interesting a-typical control problems.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2013, 33, 1; 89-109
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimal control of ∞-dimensional stochastic systems via generalized solutions of HJB equations
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729348.pdf
    Data publikacji:
    2001
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    optimal control
    stochastic systems
    infinite dimension
    HJB equation
    stationary feedback control
    Opis:
    In this paper, we consider optimal feedback control for stochastc infinite dimensional systems. We present some new results on the solution of associated HJB equations in infinite dimensional Hilbert spaces. In the process, we have also developed some new mathematical tools involving distributions on Hilbert spaces which may have many other interesting applications in other fields. We conclude with an application to optimal stationary feedback control.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2001, 21, 1; 97-126
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Weak compactness in the space of operator valued measures $M_ba(Σ,(X,Y))$ and its applications
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729361.pdf
    Data publikacji:
    2011
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    space of operator valued measures
    weak compactness
    semigroups of bounded linear operators
    optimal structural control
    Opis:
    In this note we present necessary and sufficient conditions characterizing conditionally weakly compact sets in the space of (bounded linear) operator valued measures $M_{ba}(Σ,(X,Y))$. This generalizes a recent result of the author characterizing conditionally weakly compact subsets of the space of nuclear operator valued measures $M_{ba}(Σ,₁(X,Y))$. This result has interesting applications in optimization and control theory as illustrated by several examples.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2011, 31, 2; 231-247
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimal control of systems determined by strongly nonlinear operator valued measures
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729396.pdf
    Data publikacji:
    2008
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    evolution equations
    strongly nonlinear operator valued measures
    existence of solutions
    regularity properties
    optimal control
    Opis:
    In this paper we consider a class of distributed parameter systems (partial differential equations) determined by strongly nonlinear operator valued measures in the setting of the Gelfand triple V ↪ H ↪ V* with continuous and dense embeddings where H is a separable Hilbert space and V is a reflexive Banach space with dual V*. The system is given by
    dx + A(dt,x) = f(t,x)γ(dt) + B(t)u(dt), x(0) = ξ, t ∈ I ≡ [0,T]
    where A is a strongly nonlinear operator valued measure mapping Σ × V to V* with Σ denoting the sigma algebra of subsets of the set I and f is a nonlinear operator mapping I × H to H, γ is a countably additive bounded positive measure and the control u is a suitable vector measure. We present existence, uniqueness and regularity properties of weak solutions and then prove the existence of optimal controls (vector valued measures) for a class of control problems.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2008, 28, 1; 165-189
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Vector and operator valued measures as controls for infinite dimensional systems: optimal control
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729468.pdf
    Data publikacji:
    2008
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    evolution equations
    Banach spaces
    operator valued measures
    strong operator topology
    existence of solutions
    optimal control
    Opis:
    In this paper we consider a general class of systems determined by operator valued measures which are assumed to be countably additive in the strong operator topology. This replaces our previous assumption of countable additivity in the uniform operator topology by the weaker assumption. Under the relaxed assumption plus an additional assumption requiring the existence of a dominating measure, we prove some results on existence of solutions and their regularity properties both for linear and semilinear systems. Also presented are results on continuous dependence of solutions on operator and vector valued measures, and other parameters determining the system which are then used to prove some results on control theory including existence and necessary conditions of optimality. Here the operator valued measures are treated as structural controls. The paper is concluded with some examples from classical and quantum mechanics and a remark on future direction.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2008, 28, 1; 95-131
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Impulsive perturbation of C₀-semigroups and stochastic evolution inclusions
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729564.pdf
    Data publikacji:
    2002
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    impulsive perturbations
    C₀-semigroups
    stochastic systems
    differential inclusions
    vector measures
    impulsive controls
    Opis:
    In this paper, we consider a class of infinite dimensional stochastic impulsive evolution inclusions. We prove existence of solutions and study properties of the solution set. It is also indicated how these results can be used in the study of control systems driven by vector measures.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2002, 22, 1; 125-149
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimal control of general McKean-Vlasov stochastic evolution equations on Hilbert spaces and necessary conditions of optimality
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729626.pdf
    Data publikacji:
    2015
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    McKean-Vlasov stochastic differential equation
    Hilbert spaces
    relaxed controls
    existence of optimal controls
    Opis:
    In this paper we consider controlled McKean-Vlasov stochastic evolution equations on Hilbert spaces. We prove existence and uniqueness of solutions and regularity properties thereof. We use relaxed controls, adapted to a current of sub-sigma algebras generated by observable processes, and taking values from a Polish space. We introduce an appropriate topology based on weak star convergence. We prove continuous dependence of solutions on controls with respect to appropriate topologies. Theses results are then used to prove existence of optimal controls for Bolza problems. Then we develop the necessary conditions of optimality based on semi-martingale representation theory on Hilbert spaces. Next we show that the adjoint processes arising from the necessary conditions optimality can be constructed from the solution of certain BSDE.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2015, 35, 2; 165-195
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Topological dual of $B_∞(I, ₁(X,Y))$ with application to stochastic systems on Hilbert space
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729390.pdf
    Data publikacji:
    2009
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    representation theory
    topological dual
    finitely additive operator-valued measures
    polish space
    Hilbert space
    stochastic systems
    structural control
    uncertainty abatement
    Opis:
    In this paper, we prove that the topological dual of the Banach space of bounded measurable functions with values in the space of nuclear operators, furnished with the natural topology, is isometrically isomorphic to the space of finitely additive linear operator-valued measures having bounded variation in a Banach space containing the space of bounded linear operators. This is then applied to a stochastic structural control problem. An optimal operator-valued measure, considered as the structural control, is to be chosen so as to minimize fluctuation (volatility). Both existence of optimal policy and necessary conditions of optimality are presented including a conceptual algorithm.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2009, 29, 1; 67-90
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A relaxation theorem for partially observed stochastic control on Hilbert space
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729417.pdf
    Data publikacji:
    2007
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    partially observed control
    infinite dimensional Hilbert space
    relaxed controls
    Zakai equation
    Opis:
    In this paper, we present a result on relaxability of partially observed control problems for infinite dimensional stochastic systems in a Hilbert space. This is motivated by the fact that measure valued controls, also known as relaxed controls, are difficult to construct practically and so one must inquire if it is possible to approximate the solutions corresponding to measure valued controls by those corresponding to ordinary controls. Our main result is the relaxation theorem which states that the set of solutions corresponding to ordinary controls is weakly dense in the set of solutions corresponding to relaxed controls. This is presented in Theorem 5.3 after giving some existence results on optimal controls for the infinite dimensional Zakai equation used for its proof.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2007, 27, 2; 295-314
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Infinite dimensional uncertain dynamic systems on Banach spaces and their optimal output feedback control
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729515.pdf
    Data publikacji:
    2015
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    partially observed
    uncertain systems
    stochastic systems
    operator valued functions
    feedback operators
    existence of optimal operators in the presence of uncertainty
    Opis:
    In this paper we consider a class of partially observed semilinear dynamic systems on infinite dimensional Banach spaces subject to dynamic and measurement uncertainty. The problem is to find an output feedback control law, an operator valued function, that minimizes the maximum risk. We present a result on the existence of an optimal (output feedback) operator valued function in the presence of uncertainty in the system as well as measurement. We also consider uncertain stochastic systems and present similar results on the question of existence of optimal feedback laws.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2015, 35, 1; 65-87
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Stochastic evolution equations on Hilbert spaces with partially observed relaxed controls and their necessary conditions of optimality
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729524.pdf
    Data publikacji:
    2014
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    differential equations
    Hilbert spaces
    relaxed controls
    optimal control
    necessary conditions of optimality
    Opis:
    In this paper we consider the question of optimal control for a class of stochastic evolution equations on infinite dimensional Hilbert spaces with controls appearing in both the drift and the diffusion operators. We consider relaxed controls (measure valued random processes) and briefly present some results on the question of existence of mild solutions including their regularity followed by a result on existence of partially observed optimal relaxed controls. Then we develop the necessary conditions of optimality for partially observed relaxed controls. This is the main topic of this paper. Further we present an algorithm for computation of optimal policies followed by a brief discussion on regular versus relaxed controls. The paper is concluded by an example of a non-convex problem which is readily solvable by our approach.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2014, 34, 1; 105-129
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimal control of impulsive stochastic evolution inclusions
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729552.pdf
    Data publikacji:
    2002
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    impulsive perturbations
    C₀-semigroups
    stochastic systems
    differential inclusions
    vector measures
    optimal controls
    Opis:
    In this paper, we consider a class of infinite dimensional stochastic impulsive evolution inclusions driven by vector measures. We use stochastic vector measures as controls adapted to an increasing family of complete sigma algebras and prove the existence of optimal controls.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2002, 22, 2; 155-184
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A general class of McKean-Vlasov stochastic evolution equations driven by Brownian motion and Lèvy process and controlled by Lèvy measure
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729570.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    McKean-Vlasov stochastic differential equation
    Hilbert spaces
    existence of optimal controls
    Opis:
    In this paper we consider McKean-Vlasov stochastic evolution equations on Hilbert spaces driven by Brownian motion and L`evy process and controlled by L`evy measures. We prove existence and uniqueness of solutions and regularity properties thereof. We consider weak topology on the space of bounded Le´vy measures on infinite dimensional Hilbert space and prove continuous dependence of solutions with respect to the Le´vy measure. Then considering a certain class of Le´vy measures on infinite as well as finite dimensional Hilbert spaces, as relaxed controls, we prove existence of optimal controls for Bolza problem and some simple mass transport problems
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2016, 36, 2; 181-206
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Measure valued solutions for stochastic evolution equations on Hilbert space and their feedback control
    Autorzy:
    Ahmed, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/729584.pdf
    Data publikacji:
    2005
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    stochastic differential equations
    Hilbert space
    measurable vector fields
    finitely additive measure solutions
    optimal feedback controls
    Opis:
    In this paper, we consider a class of semilinear stochastic evolution equations on Hilbert space driven by a stochastic vector measure. The nonlinear terms are assumed to be merely continuous and bounded on bounded sets. We prove the existence of measure valued solutions generalizing some earlier results of the author. As a corollary, an existence result of a measure solution for a forward Kolmogorov equation with unbounded operator valued coefficients is obtained. The main result is further extended to cover Borel measurable drift and diffusion which are assumed to be bounded on bounded sets. Also we consider control problems for these systems and present several results on the existence of optimal feedback controls.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2005, 25, 1; 129-157
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Controllability of evolution equations and inclusions driven by vector measures
    Autorzy:
    Ahmed, N.U.
    Powiązania:
    https://bibliotekanauki.pl/articles/729615.pdf
    Data publikacji:
    2004
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    controlability
    impulsive systems
    differential inclusions
    Hilbert spaces
    vector valued measures
    C₀ semigroups
    Opis:
    In this paper, we consider the question of controllability of a class of linear and semilinear evolution equations on Hilbert space with measures as controls. We present necessary and sufficient conditions for weak and exact (strong) controllability of a linear system. Using this result we prove that exact controllability of the linear system implies exact controllability of a perturbed semilinear system. Controllability problem for the semilinear system is formulated as a fixed point problem on the space of vector measures and is concluded controllability from the existence of a fixed point. Our results cover impulsive controls as well as regular controls.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2004, 24, 1; 49-72
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Improved photoresponse of porous silicon photodetectors by embedding CdS nanoparticles
    Autorzy:
    Abd, Ahmed N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1193949.pdf
    Data publikacji:
    2015
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    CdS
    Nanoparticles
    PSi
    Photodetector
    SEM
    XRD
    Opis:
    In this research, the nanocrystalline porous silicon (PSi) films are prepared by electrochemical etching of p types silicon wafers with 15 mA/cm2 etching current densities and 15 min etching time on the formation nanosized pore array. PSi was characterized by the measurement of XRD, FTIR spectroscopy and atomic force microscopy properties (AFM). We have estimated crystallites size from X-Ray diffraction about nanoscale for PSi and Atomic Force microscopy confirms the nanometric size Chemical fictionalization during the electrochemical etching show on the surface chemical composition of PSi. The atomic force microscopy investigation shows the rough silicon surface. Also, it is reported the preparation of colloidal CdS nanoparticles NPs prepared by laser ablation in liquid (LAL) technique by irradiating with a Nd:YAG laser pulses CdS target immersed in methanol and varying the laser fluence 1.32 J/cm2. The structural, morphological and optical of CdS NPs has been studied. XRD measurement disclosed that the CdS NPs were of wurtzite hexagonal crystal structure. Transmission electron microscopy (TEM) investigation revealed that the synthesized CdS particles are spherical and have an average particle size in the range of (25 nm). AFM investigations showed that the produced CdS particles have ball-shape with good disposability. The energy band gap of CdS NPs prepared with 1.32 J/cm2 laser fluence has been determined from optical properties and found to be in the range (2.9 eV). Optical constants of CdS NPs were determined from transmittance and reflectance spectra.The effect of CdS NPs diffusion on properties of PSi Photodetector have reported which reveals that improving in (Al/PSi/Si/Al). The results show that a linear relationship between 1/C2 and reverse bias voltage was obtained. The built-in potential have values depending on the etching time current density and laser flunce. Al/CdSe/PSi/Si/Al photodetector hetrojunction have two peaks of response located at 415 nm and (700 -800nm) with max sensitivity 0.6 A/W. The maximum specific detectivity is 6.8×〖10〗^12 cm•〖Hz〗^(1/2) 〖•W〗^(-1) at 770 nm wavelength.
    Źródło:
    World Scientific News; 2015, 19; 32-49
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Stochastic diffrential equations on Banach spaces and their optimal feedback control
    Autorzy:
    Ahmed, N.U.
    Powiązania:
    https://bibliotekanauki.pl/articles/952179.pdf
    Data publikacji:
    2012
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    stochastic differential equations
    Banach spaces
    optimal feedback control
    objective functionals
    Lévy-Prohorov metric
    Hausdorff dimension
    time-optimal problems
    Opis:
    In this paper we consider stochastic differential equations on Banach spaces (not Hilbert). The system is semilinear and the principal operator generating a C₀-semigroup is perturbed by a class of bounded linear operators considered as feedback operators from an admissible set. We consider the corresponding family of measure valued functions and present sufficient conditions for weak compactness. Then we consider applications of this result to several interesting optimal feedback control problems. We present results on existence of optimal feedback operators.
    Źródło:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2012, 32, 1; 87-109
    1509-9407
    Pojawia się w:
    Discussiones Mathematicae, Differential Inclusions, Control and Optimization
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Some Physical Properties of Copper Oxide Thin Films Prepared by Electrolysis Method
    Autorzy:
    Oudah, Mustafa H.
    Mazin, H. Hasan
    Abd, Ahmed N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1065248.pdf
    Data publikacji:
    2019
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    copper oxide
    drop-casting method
    electrolysis
    quantum size effect
    thin films
    Opis:
    The aim of this paper is to study the properties of copper oxide thin films prepared by electrolysis method and deposited on glass substrates by drop-casting method at different annealing temperatures. Copper oxide colloidal was successfully prepared by electrolysis method. The X-ray diffraction confirms the polycrystalline structure of the films. Atomic force microscopy shows that the increase in the annealing temperature improves the surface morphology, increases the grain size and removes the cracks. The best optical transmittance was for the film annealed at 200 ºC. The bandgap decreases from 3.35 eV to 3.15 eV as a result of increasing the annealing temperature. The wide bandgap that obtained in this study is due to quantum size effect.
    Źródło:
    World Scientific News; 2019, 135; 59-70
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of water treatment plants quality in Basrah Province, by factor and cluster analysis
    Autorzy:
    Al Saad, Zainb A.A.
    Hamdan, Ahmed N.A.
    Powiązania:
    https://bibliotekanauki.pl/articles/293213.pdf
    Data publikacji:
    2020
    Wydawca:
    Instytut Technologiczno-Przyrodniczy
    Tematy:
    cluster analysis (CA)
    factor analysis (FA)
    multivariate statistics
    the Shatt Al Arab River
    water quality
    water treatment plant
    Opis:
    The Shatt Al Arab River (SAAR) is a major source of raw water for most water treatment plants (WTP’s) located along with it in Basrah province. This study aims to determine the effects of different variables on water quality of the SAAR, using multivariate statistical analysis. Seventeen variables were measured in nine WTP’s during 2017, these sites are Al Hussain (1), Awaissan (2), Al Abass (3), Al Garma (4), Mhaigran (5), Al Asmaee (6), Al Jubaila (7), Al Baradia (8), Al Lebani (9). The dataset is treated using principal component analysis (PCA) / factor analysis (FA), cluster analysis (CA) to the most important factors affecting water quality, sources of contamination and the suitability of water for drinking and irrigation. Three factors are responsible for the data structure representing 88.86% of the total variance in the dataset. CA shows three different groups of similarity between the sampling stations, in which station 5 (Mhaigran) is more contaminated than others, while station 3 (Al Abass) and 6 (Al Asmaee) are less contaminated. Electrical conductivity (EC) and sodium adsorption ratio (SAR) are plotted on Richard diagram. It is shown that the samples of water of Mhaigran are located in the class of C4-S3 of very high salinity and sodium, water samples of Al Abass station, are located in the class of C3-S1 of high salinity and low sodium, and others are located in the class of C4-S2 of high salinity and medium sodium. Generally, the results of most water quality parameters reveal that SAAR is not within the permissible levels of drinking and irrigation.
    Źródło:
    Journal of Water and Land Development; 2020, 46; 10-19
    1429-7426
    2083-4535
    Pojawia się w:
    Journal of Water and Land Development
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Cotton leaf blight disease caused by Alternaria alternata in Sudan
    Autorzy:
    Mohamed, O.E.
    Beshir, M.M.
    Ahmed, N.E.
    Powiązania:
    https://bibliotekanauki.pl/articles/2084617.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Alternaria alternata
    conidia
    Gossypium spp.
    internal transcribed spacer
    (ITS)
    morphological variability
    pathogenicity
    Opis:
    Genetically modified Bt cotton (Gossypium hirsutum) leaves with typical symptoms of Alternaria early blight disease resembling that of tomato and potato were observed in the main cotton growing schemes in Sudan. Symptoms on leaves appeared as either brown 2leaf spot with gray centers or leaf blight with concentric rings. Pathogenicity tests using isolates with both symptoms showed that the isolated fungi were highly pathogenic to both G. hirsutum and G. barbadense cotton varieties. Alternaria alternata isolated from infected tomato and potato leaves with early blight symptoms was included for comparison. Microscopic examination showed that the mean length of conidia from cotton, tomato and potato isolates ranged from 26.25 to 45.45 µm, while the width ranged from 9.56 to 13.64 µm. The mean number of transverse septa among all isolates was 3.4 to 5.7 and the peak length ranged from 3.75 to 7.8 µm. Based on morphological characteristics the two isolates from cotton were identified as A. alternata. Genomic DNA was extracted directly from fungal cultures grown on potato dextrose agar (PDA) plates using a Zymo Research Quick DNA kit. A species-specific primer using the internal transcribed spacer ribosomal DNA (ITS rDNA) PCR scoring indicated the presence of A. alternata using primer pair ITS4/ITS5. Amplifications of the internal transcribed spacer region of 600 bp revealed 100% identity of the isolated fungus from cotton with A. alternata from tomato and potato. These data oblige us to reconsider the presence of A. alternata in the four main cotton growing schemes in Sudan while these symptoms have always been described for tomato and potato early blight disease.
    Źródło:
    Journal of Plant Protection Research; 2019, 59, 3; 412-417
    1427-4345
    Pojawia się w:
    Journal of Plant Protection Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spectroscopic Methods Studies in Polymer
    Autorzy:
    Rahi, Saad Khalid
    Hassan, Ehssan Salah
    Abd, Ahmed N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1190136.pdf
    Data publikacji:
    2016
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    ESCA
    polymer
    Fluorescence spectra
    Excitation wavelength
    Opis:
    The physico – chemical changes induced in polymers following to radiation can be studied by a range of spectroscopic techniques. Recent developments in instrumentation and data analysis procedures in electronic, vibrational and magnetic resonance spectroscopes have provided considerable new insights, into polymer structure and behavior. The applications of these spectroscopic methods in polymer studies are reviewed with emphasis on their utility in investigations of radiation effects on macromolecules
    Źródło:
    World Scientific News; 2016, 42; 41-53
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of molarity on the structural and optical properties of ZnO thin films deposit by CSP
    Autorzy:
    Habubi, Nadir F.
    Abood, Ziad M.
    Algamel, Ahmed N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1193915.pdf
    Data publikacji:
    2015
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Urbach energy
    ZnO
    ZnO thin films
    optical properties
    structural properties
    Opis:
    ZnO thin films have been prepared by chemical spray pyrolysis technique CSP). XRD pattern reveals that the preferred orientation was varied with concentration, topography analysis was done by AFM micrograph which confirm the existence of nonstructural films. The optical properties was done by recorded the transmittane and absorbance which were affected by an increase in concentration. The values of optical energy gap obtained from Tauc relation were 3.17, 3.18 and 3.19 eV for 0.05, 0.1 and 0.5 M respectively. Urbach energy confirms the decrease in band tail as the concentration increase.
    Źródło:
    World Scientific News; 2015, 22; 55-69
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fabrication and Characterization of Porous Silicon
    Autorzy:
    Duaa, Jabbar Hussein
    Alzubaidy, Muneer H. Jaduaa
    Abd, Ahmed N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1157178.pdf
    Data publikacji:
    2018
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Anodization
    Nanocrystalline porous silicon
    XRD
    porous silicon
    Opis:
    In this work, nanocrystalline porous silicon layers were fabricated by photoelectrochemical etching of n type silicon (n-Si) wafer. Different etching time (15, 20, 25 and 30) min and 10 mA/cm2 current density were tested to study their effect on the formation nanosized pore array. Porous silicon is investigation by X-Ray diffractions (XRD) and atomic force microscopy properties (AFM). Crystallites size was estimated by X-Ray diffraction. Atomic Force microscopy confirmed the nonmetric size Chemical Anodization the electrochemical etching was noticed of PS. The atomic force microscopy investigation showed the rough silicon surface which increased with etching time porous structure nucleates which leads to an increase in the depth and width (diameter) of surface pits.
    Źródło:
    World Scientific News; 2018, 94, 2; 321-328
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Biological synthesis of Titanium Dioxide nanoparticles by Curcuma longa plant extract and study its biological properties
    Autorzy:
    Abdul Jalill, Raghad DH.
    Nuaman, Rasha S.
    Abd, Ahmed N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1182934.pdf
    Data publikacji:
    2016
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    biosynthesis
    curcuma longa
    damping-off
    nanoparticles
    plant
    tio2
    Opis:
    The objective of this study was biosynthesis of titanium dioxide nanoparticles (TiO2 NPs) using Curcuma longa aqueous extract and characterize them. Study their effect on the growth, sporulation, pathogenicity of Fusarium graminearum and some wheat plants parameters compared with standards industrials nanoparticles. C. longa aquatic extract was used to biosynthesis TiO2 NPs by two methods. At first method, TiO2 was found in both colloidal solutions (CS) and nanopawder while it found in jest nanopawder in second method. All biosynthetic nanoparticles were in nano size. It was: 91.37 nm, 76.36 nm of (CS) and nanopawder for first methods respectively while it was 92.6 nm of nanopawder in second method. All nanoparticles have good optical properties. Crystal’s shape of nanopawder were in three form: anatase, rutilr and brookite and it was anatase in colloidal solutionat first method while it was pure anatase innanopawder when at second method. The average crystallite size of was calculate by Scherer's equation, it was 43.088 nm and 22.881 nm for nanopawder and colloidal solution respectively at first method. It was 45.808 nm for nanopawder at second method. All concentrations of nanoparticles were reduced fungal and spores. These decreasing were more effective using biosynthetic compare with industrial synthetic nanoparticles. There were reductions in damping-off caused by F. graminearum by biosynthetic NBs in both varieties of plant (Al-Rasheed and Tamuze-2). These was better than the effect of industrial synthetic nanoparticles. The resistance to damping off and the growth of plant in Al-Rasheed variety was more sensitive compared with Tamuze-2 variety especially at higher concentrations. There were decrease in all plant's parameters at most concentrations of TiO2 biological synthetic compare with industrial synthetic nanoparticles in Al-Rasheed variety, while there were inductions in some plant's parameters by biosynthetic nanoparticles compared with industrial synthetic in Tamuze-2 variety. Finally, C. longa can be used to biosynthesis TiO2 NPs with good biological properties.
    Źródło:
    World Scientific News; 2016, 49, 2; 204-222
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Theoretical model to determine the Porosity and refractive index of porous silicon type-n by using Atomic force microscope
    Autorzy:
    Abdulridha, Wasna'a M.
    Abd, Ahmed N.
    Dawood, Mohammed O.
    Powiązania:
    https://bibliotekanauki.pl/articles/1193012.pdf
    Data publikacji:
    2016
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Atomic Force Microscope
    Porous silicon
    n-PS
    porosity
    refractive index
    thickness
    Opis:
    Porous silicon (PS) layer was produced by photochemical etching process at (5, 7, 10, 12 and 15) etching time and 7 mA/cm2 current density then after investigation by Atomic Force Microscope (AFM) the thickness of PS layer from about 3.4 µm to 15.8 µm was determined. The surface of porous silicon is formed from small pyramids with porous structure, where the porosity of n-PS is from ≈ (32-72%). Porous silicon layer formed on the silicon substrates by photochemical etching contains also the nanopores with diameter about (16.41-42) nm in current density (7mA/cm2). The porosity and thickness was determined from AFM results and compared with the result from the usually measured porosity and thickness through a gravimetric method we found that the values of porosity and thickness calculated from two methods are approximately similar to each other with few difference, the influence of structure changes on optical properties such as refractive index, which decreases exponentially with porosity.
    Źródło:
    World Scientific News; 2016, 28; 29-40
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Higher Solar Cell Efficiency Achieved with ZnO/Si heterojuction
    Autorzy:
    Ayad, jumaah kadhim
    Muneer, H. Jaduaa Alzubaidy
    Abd, Ahmed N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1161880.pdf
    Data publikacji:
    2018
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    AFM
    XRD
    ZnO/Si
    chemical method
    conversation efficiency
    solar cell
    Opis:
    In this work, the zinc oxide nanoparticles were prepared chemically and deposited by casting style on glass bases and treated thermally at a temperature of 600 °C. The study focused on Optical and structural properties of thin films. An optical advantages of Zinc Oxide (ZnO) were characterized by using ultraviolet visible Spectroscopy. And the structure by using X-Ray Diffraction and (AFM). The optical advantages of thin films were studied by recording the transmittance spectra of wavelengths range (300-900 nm). The energy gap was calculated using tauc equation and is found (3 eV). I-V properties of the solar cell under light at 40 mW/cm2 flounce was investigated. The open circuit Voltage (Voc) was 33 and Short-circuit density (Isc) was 0.017 mA. This measurements show that the fill factor (F.F) and conversation efficiency (η), were 55% and 9.9% respectively.
    Źródło:
    World Scientific News; 2018, 112; 226-234
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation on the structural, optical and topographical behavior of Cadmium oxide polycrystalline thin films using electrochemical depositing method at different times
    Autorzy:
    Abd, Ahmed N.
    Dawood, Mohammed O.
    Hassoni, Majid H.
    Hussein, Ali A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1192094.pdf
    Data publikacji:
    2016
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Cadmium oxide
    thin film
    optical characteristics of film
    electrochemical depositing method
    Opis:
    The optical and structure properties of Cadmium oxide (CdO) thin film prepared by electrochemical deposition method at different times (15, 30 and 60) min were investigated in this paper. Results of optical Transmission, absorption, reflection spectra, optical conductance, refractive index, extension coefficient, real and imaginary dielectric constants studies are reported. The optical transmittance of the CdO thin film which formed at room temperature was 20% at wavelength ≈350 nm then increases to 60% at wavelength ≈1100 nm for thin film of CdO. The band-gap was also calculated from the equation relating absorption coefficient with the wavelength. The energy band gap changes from 2.3eV (Bulk CdO) to 2.45eV (CdO thin film). The plotted graphs show the optical characteristics of the film which varied with the wavelength and the photon energy. The optical conductance and band-gap indicated that the film is transmitting within the visible range. The dielectric constant and optical conductance of the film initially decreases slowly with increase in photon energy. The extinction coefficient and refractive index of the films also evaluated, which affected with the change in transmittance. The structure of synthesised CdO thin film was analyzed by X-ray diffraction XRD which revealed that the CdO thin film are polycrystalline and have several peaks of cubic face structure. The crystallite size, dislocation density, microstrain and number of dislocations of the thin film were calculated and listed.
    Źródło:
    World Scientific News; 2016, 37; 249-264
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effects of Triangular Core Rotation of a Hybrid Porous Core Terahertz Waveguide
    Autorzy:
    Ali, S.
    Ahmed, N.
    Alwee, S.
    Islam, M.
    Rana, S.
    Bhuiyan, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/227154.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    porous core waveguide
    THz waveguide
    flat EML
    hybrid design
    flat dispersion
    triangular design
    core rotation
    Opis:
    In this paper, we investigate the effects for rotating the triangular core air hole arrangements of a hybrid design porous core fiber. The triangular core has been rotated in anticlockwise direction to evaluate the impact on different waveguide properties. Effective Material Loss (EML), confinement loss, bending loss, dispersion characteristics and fraction of power flow are calculated to determine the impacts for rotating the triangular core. The porous fiber represented here has a hybrid design in the core area which includes circular rings with central triangular air hole arrangement. The cladding of the investigated fiber has a hexagonal array of air hole distribution. For optimum parameters the reported hybrid porous core fiber shows a flat EML of ±0.000416 cm⁻¹ from 1.5 to 5 terahertz (THz) range and a near zero dispersion of 0.4±0.042 ps/THz/cm from 1.25 to 5.0 THz. Negligible confinement and bending losses are reported for this new type of hybrid porous core design. With improved concept of air hole distribution and exceptional waveguide properties, the reported porous core fiber can be considered as a vital forwarding step in this field of research.
    Źródło:
    International Journal of Electronics and Telecommunications; 2017, 63, 1; 25-31
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Minimizing of tunneling effect on existing infrastructure in Egypt
    Autorzy:
    Asker, Kamel I.
    Fouad, Mohamed T.
    Bahr, Mohamed A.
    El-Attar, Ahmed N.
    Powiązania:
    https://bibliotekanauki.pl/articles/35525187.pdf
    Data publikacji:
    2021
    Wydawca:
    Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
    Tematy:
    tunneling
    grouting
    field measurements
    Abaqus
    Al-Azhar twin tunnel
    Opis:
    A set of parametric studies by using the Abaqus software is conducting to investigate the effective method to seal the CWO sewer from the tunneling process. These methods include: (i) two deep grouted walls, (ii) adjacent slurry piles, (iii) bored reinforced concrete piles assisted with slurry piles, and (iv) grouted block confining the twin tunnel wall. Based on the results of parametric studies. Most of the protective studied technique was effective on reducing the tunneling effect on the ground movements.
    Źródło:
    Scientific Review Engineering and Environmental Sciences; 2021, 30, 1; 3-15
    1732-9353
    Pojawia się w:
    Scientific Review Engineering and Environmental Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic field evaluation around 400 KV underground power cable under harmonics effects
    Autorzy:
    Boudjella, Houari
    Ayad, Ahmed N. E. I.
    Rouibah, Tahar
    Larouci, Benyekhlef
    Alghamdi, Thamer A. H.
    Althobaiti, Ahmed
    Ghoneim, Sherif S. M.
    Tayeb, Abdelkader Si
    Powiązania:
    https://bibliotekanauki.pl/articles/2096182.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
    Tematy:
    electric power cables
    magnetic field
    harmonics
    shielding
    400 kV underground power system
    kabel energetyczny
    pole magnetyczne
    harmoniczne
    Opis:
    Power lines or underground power cables generate electromagnetic interaction with other objects near to them. This study evaluates the magnetic field emitted by underground extra high voltage cables. The presented work aims to show a numerical simulation of the magnetic field of a buried 400 kV underground power line, which is used as a novel prototype in several countries at a short distance. The underground power cable study, in the presence of the current harmonics at different positions, with time variation by finite element resolution, using Comsol Multiphysics with Matlab software in two dimensions. The simulation results illustrate the magnetic flux density variation-in terms of amplitude and distribution as a function of different actual harmonics rates. The underground cable performance and magnetic field have affected by the harmonics effects. The maximum magnetic induction levels generated by significant harmonics are superior to the limits recommended by the international standard norms. In this paper, shielding has been used as an appropriate remedy to attenuate the magnetic field.
    Źródło:
    Diagnostyka; 2022, 23, 2; art. no. 2022209
    1641-6414
    2449-5220
    Pojawia się w:
    Diagnostyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the Effects of Code Cardinality for TH-PPM Ultra Wideband Systems
    Autorzy:
    Mahfuz, M. U.
    Ahmed, K. M.
    Rajatheva, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/307946.pdf
    Data publikacji:
    2008
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    code cardinality
    multiple user interference
    TH-PPM
    ultra wideband
    Opis:
    This paper demonstrates the effects of code cardinality at transmitter section on bit error rate (BER) performance of time hopping pulse position modulation (TH-PPM) based ultra wideband (UWB) indoor radio communication. In the transmitter, different code cardinality values have been chosen and correspondingly the effects on BER of the system have been investigated. The recently accepted IEEE 802.15.3a model of the UWB channel has been used as the propaga- tion channel model in indoor environment. Results show that the system BER performance is significantly dependent on the code cardinality value of time hopping code. For such higher code cardinality values as in the range from 30 to 50, the BER performance degrades severely. Finally, code cardinality in the range from 10 to 15 has been recommended for TH-PPM system in UWB indoor communications providing better BER performance for the same system data rate requirement
    Źródło:
    Journal of Telecommunications and Information Technology; 2008, 4; 73-78
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimum receiver performance of TH-PPM ultra wideband system in multiple user interference
    Autorzy:
    Mahfuz, M. U.
    Ahmed, K. M.
    Rajatheva, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/308545.pdf
    Data publikacji:
    2007
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    optimum receiver performance
    TH-PPM
    ultra wideband
    multiple user interference
    Opis:
    This paper demonstrates optimum receiver performance in terms of bit error rate (BER) for time hopping pulse position modulation (TH-PPM) ultra wideband (UWB) system in multiple user interference environment for indoor radio communication. Equal gain combining and selective gain combining have been demonstrated in terms of ideal RAKE (ARAKE), selective RAKE (SRAKE) and partial RAKE (PRAKE) receiver performances. The recently accepted IEEE 802.15.3a model of the UWB channel has been used to describe UWB propagation in indoor environment. Two channel scenarios named CM-1 and CM-3 for IEEE 802.15.3a channel model have been investigated principally. Finally, this paper concludes with an approximation of equivalence of number of fingers in SRAKE and PRAKE receivers as well as an indication of SNR gains achievable as the RAKE finger number is increased, espe- cially with multiple user interference (MUI), for a 16.6 Mbit/s UWB system.
    Źródło:
    Journal of Telecommunications and Information Technology; 2007, 4; 77-84
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental study of hydraulic sweeps in horizontal wells
    Badanie możliwości oczyszczania hydraulicznego w otworach poziomych
    Autorzy:
    Nguyen, T. N.
    Miska, S. Z.
    Yu, M.
    Takach, N. E.
    Ahmed, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/300465.pdf
    Data publikacji:
    2010
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    otwory poziome
    oczyszczanie hydrauliczne
    horizontal wells
    hydraulic sweeps
    Opis:
    Drilling fluid sweeps are commonly run in the field to help clean the borehole of cuttings that have not been removed with normal drilling fluid circulation, especially in high angle or extended reach wells where efficient hole cleaning is more difficult to maintain. This study focuses on the use of "conventional" and "enhanced" sweeps in horizontal well bores. Not much information pertaining to the use of drilling fluid sweeps is available in the literature. Furthermore, there has been a lack of agreement as to which types of sweep fluids are most effective. Conventional sweeps most often include high viscosity fluids, high density fluids or a combination of both. In addition to conventional sweep fluids, an attempt was made to use enhanced sweep fluids, in which surfactants are used to attach cuttings to oil droplets that are intentionally introduced to the drilling fluid system. Because of their low density, oil droplets can have the ability to keep cuttings particles in suspension. The use of oil droplets is a new concept in cleaning horizontal and deviated wellbores. This work focuses on experimental analysis of sweep fluids with the goal of quantifying the sweep "efficiency". A small-scale sweep loop (SSL) was mainly used to conduct sweep experiments. Moreover, some experiments were carried out in a field-scale flow loop that operates at low-pressure ambient temperature (LPAT) conditions. Results show that pipe rotation plays a very important role in improving hole cleaning. Particularly, the improvement is substantial with high-viscosity fluids. The rotation of pipe has agitation effect that forces the cuttings particles into the main flow and facilitates the removal process. As anticipated, increasing the flow rate enhances the sweep efficiency or cuttings removal regardless of the drillpipe rotation. Furthermore, the study suggests that with a more rigorous evaluation of sweep efficiency, one can objectively determine the type and frequency of drilling sweep. The results of this study are useful for selection of the optimal sweep fluid.
    Płuczki czyszczące są powszechnie stosowane do oczyszczania otworów z pozostałości zwiercin, których nie udało się wynieść na powierzchnię za pomocą tradycyjnych płynów płuczkowych, głównie w przypadku otworów kierunkowych i rozgałęzionych, gdzie możliwość oczyszczenia jest ograniczona. Badania skoncentrowały się na wykorzystaniu konwencjonalnych i ulepszonych systemów czyszczących w otworach kierunkowych. W literaturze niezbyt wiele można znaleźć informacji na ten temat. Co więcej, brak jest zgody co do tego, która płuczka czyszcząca jest najskuteczniejsza. Tradycyjne płuczki czyszczące często zawierają płyny o wysokiej lepkości i/lub gęstości. Ponadto podjęto próbę stworzenia ulepszonych płuczek czyszczących, w których zastosowane surfaktanty mają powodować przyklejanie się zwiercin do drobin oleju, który celowo wprowadzono do systemu płuczkowego. Ze względu na niską gęstość, krople oleju utrzymują zwierciny w zawieszeniu. Zastosowanie kropli oleju to nowa koncepcja oczyszczania otworów horyzontalnych. W artykule skoncentrowano się na przeanalizowaniu płuczek czyszczących mających na celu zwiększenie skuteczności oczyszczania. Do badań z reguły stosowano mały obieg czyszczący SSL (small-scale sweep loop). Niektóre eksperymenty prowadzono na złożu w warunkach niskiego ciśnienia i temperatury otoczenia. Wyniki pokazują, że ruch rur odgrywa istotną rolę w zwiększeniu skuteczności oczyszczania otworu. Służy temu również zastosowanie wysoko lepkich płuczek. Rotacja rur podrywa zwierciny doprowadzając je do głównego strumienia, wspomagając proces oczyszczania. Jak przewidywano, ruch w otworze wzmaga wydajność oczyszczania lub wynoszenia zwiercin, niezależnie od rotacji rur. Z badań wynika, że szacując bardziej rygorystycznie zdolności czyszczące, można obiektywnie określić rodzaj i częstotliwość oczyszczania. Wyniki badań pozwalają na stosowny wybór optymalnego środka czyszczącego.
    Źródło:
    Wiertnictwo, Nafta, Gaz; 2010, 27, 1--2; 307-331
    1507-0042
    Pojawia się w:
    Wiertnictwo, Nafta, Gaz
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dynamical complexity of human responses: a multivariate data-adaptive framework
    Autorzy:
    Ahmed, M.
    Rehman, N.
    Looney, D.
    Rutkowski, T.
    Mandic, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/201559.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    multivariate sample entropy
    multivariate empirical mode decomposition (MEMD)
    multivariate multiscale entropy
    complexity analysis
    multivariate complexity
    postural sway analysis
    stride interval analysis
    brain consciousness analysis
    alpha-attenuated EEG data
    Opis:
    Established complexity measures typically operate at a single scale and thus fail to quantify inherent long-range correlations in real-world data, a key feature of complex systems. The recently introduced multiscale entropy (MSE) method has the ability to detect fractal correlations and has been used successfully to assess the complexity of univariate data. However, multivariate observations are common in many real-world scenarios and a simultaneous analysis of their structural complexity is a prerequisite for the understanding of the underlying signal-generating mechanism. For this purpose, based on the notion of multivariate sample entropy, the standard MSE method is extended to the multivariate case, whereby for rigor, the intrinsic multivariate scales of the input data are generated adaptively via the multivariate empirical mode decomposition (MEMD) algorithm. This allows us to gain better understanding of the complexity of the underlying multivariate real-world process, together with more degrees of freedom and physical interpretation in the analysis. Simulations on both synthetic and real-world biological multivariate data sets support the analysis.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 3; 433-445
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Microbial degradation of lignocellulosic biomass: discovery of novel natural lignocellulolytic bacteria
    Autorzy:
    Ahmed, S.
    Rahman, S.
    Hasan, M.
    Paul, N.
    Sajib, A.A.
    Powiązania:
    https://bibliotekanauki.pl/articles/81125.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    lignocellulose
    microbial degradation
    biofuel
    cellulose
    lignin
    hemicellulose
    lignocellulolytic bacteria
    Chryseobacterium gleum
    Źródło:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2018, 99, 2
    0860-7796
    Pojawia się w:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Transient flow simulation, analysis and protection of pipeline systems
    Autorzy:
    El-Hazek, Alaa N.
    Ahmed, Menna F.
    Badawy, Neveen Abdel-Mageed
    Powiązania:
    https://bibliotekanauki.pl/articles/1844407.pdf
    Data publikacji:
    2020
    Wydawca:
    Instytut Technologiczno-Przyrodniczy
    Tematy:
    air vessel
    Bentley HAMMER model
    surge tank
    unsteady flow
    vacuum breaker valve
    water hammer
    water turbidity
    Opis:
    This paper investigated the problems and impacts of transient flow in pipeline systems due to pump power failure. The impact of different protection devices was presented to assure surge protection for the pipeline system. A model via Bentley HAMMER V8.0 Edition was employed to analyse and simulate hydraulic transients in the pipeline system, and protection alternatives were studied. Surge protection included using only an air vessel, using an air vessel and two surge tanks, and employing five air vessels and vacuum breaker. The obtained results for pressures, heads, and cavitation along the pipeline system were graphically presented for various operating conditions. Using five air vessels with vacuum breaker valve as surge protection proved to be more effective and economical against pump power failure. Changing the flow density did not have a significant impact on the pressures. For protection with an air vessel; it was concluded that the value 40% of the original diameter for inlet pipe diameter of air vessel, and the value of 2/3 of original pipe diameter were critical values for the transient pressures. Cast iron pipes proved to be the best pipe material for all studied volumes of the air vessel. For protection with an air vessel and two surge tanks; as the inlet pipe diameters increased the maximum pressures increased and the minimum pressures decreased. Regression analyses were performed obtaining equations to predict the pressures according to the inlet pipe diameter, the area of surge tank, and the pipe diameter.
    Źródło:
    Journal of Water and Land Development; 2020, 47; 47-60
    1429-7426
    2083-4535
    Pojawia się w:
    Journal of Water and Land Development
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of robotic cleaning technologies: preserving a british iconic building
    Autorzy:
    Haqqani, Ahmed A.H
    Seenu, N
    Janardhanan, Mukund
    Kuppan, Chetty RM
    Powiązania:
    https://bibliotekanauki.pl/articles/118264.pdf
    Data publikacji:
    2020
    Wydawca:
    Polskie Towarzystwo Promocji Wiedzy
    Tematy:
    wall climbing robot
    multicriteria decision analysis
    cleaning robot
    quality function deployment
    robot wspinający się po ścianie
    analiza decyzji według wielu kryteriów
    robot czyszczący
    wdrażanie funkcji jakości
    Opis:
    The engineering building of the University Leicester built-in 1963 has been a British icon for decades now. Applications of Robotic technologies are uprising nowadays, which provides a contingency to manipulate the benefits of robotics for executing challenging and precarious facade cleaning processes. This paper surveys the facade cleaning robotic technologies exist in the market. It exhibits the comparative analysis of four notorious robotic facade cleaning solutions namely Sky Pro, Gekko, BFMR (Building Façade Maintenance Robot) and Sirius_c. The comparison is executed using Multi Criteria Decision Analysis (MCDA) and Quality Function Deployment (QFD) techniques. This study analyses the performance of the robots based on the critical parameters such as water consumption, cleaning efficiency, cleaning dimensions and ease of implementation. Although none of these robotic solutions are implemented off the shelf, some adaptation on these solutions is necessary for the development of robotic techniques work successfully in real time. This paper proposes a hybrid robotic solution combining the vacuum pump adhesion and wheeled locomotion for the effective cleaning of the complex external building structure based on the MCDA and QFD analysis. It highlights the significant future research directions in this field.
    Źródło:
    Applied Computer Science; 2020, 16, 2; 95-111
    1895-3735
    Pojawia się w:
    Applied Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ocena energii rozdrabniania składników cementowych
    Energy assessment in mixture grinding of cement raw materials
    Autorzy:
    Ahmed, H. A. M.
    Al-Maghrabi, M. N.
    Haffez, G. S. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/318945.pdf
    Data publikacji:
    2007
    Wydawca:
    Polskie Towarzystwo Przeróbki Kopalin
    Tematy:
    ocena energii
    składniki cementowe
    rozdrabnianie
    energy assessment
    cement raw materials
    mixture grinding
    Opis:
    Przemysł cementowy stosuje rozdrabnianie, które zużywa dużo energii. Zatem proces rozdrabniania cementu jest ważnym zagadnieniem. Dlatego w tym artykule rozważano rozdrabnianie surowego cementu w okresowym młynie kulowym według różnych metodologii, w tym mielenie każdego składnika (glina, kwarcyt, wapień) osobno oraz mielenie ich razem jako mieszaniny trzech składników. Oceniano zużycie energii dla obu rozwiązań. Dodatkowo, w przypadku mieszaniny trzech składników, zmieniano stosunek wszystkich trzech składników. Wyniki oceniano za pomocą składu ziarnowego produktów mielenia dla odpowiednich poziomów zużycia energii i podziału zużytej energii pomiędzy składniki mieszaniny. Stwierdzono, że ilość zużytej na mielenie energii silnie wpływa na ziarnowy moduł Gaudina-Schumanna w zależności od tego, czy materiał był mielony jako mieszanina czy też nie. W przeciwieństwie do tego, wpływ zużywanej energii na dystrybucyjny moduł Gaudina-Schumanna był niewielki. Ustalono, że zmodyfikowane równanie Charlesa, stosowane do obliczania energii rozdrabniania mieszaniny, opisuje bardzo dobrze dystrybucję energii pomiędzy składnikami mieszaniny. Dystrybucja energii pomiędzy składnikami mieszaniny zależy w dużym stopniu od udziału twardych składników, które zwiększają rozdrabnialność składników miękkich. Z tego powodu kwarc wykorzystuje tylko 96% energii przewidywanej dla mieszaniny 1:2:1 dla wszystkich stosowanych poziomów zużycia energii.
    Cement industry depends mainly on grinding which is an energy intensive unit operation. Thus, understanding the behaviour of cement raw materials grinding is a vital issue. Therefore, this paper considers batch ball mill grinding of cement raw materials according to different grinding schemes, including single grinding of each component (clay quartzite, limestone) separately and grinding them together in ternary mixtures. The applied energy levels were verified for both schemes. In addition, in the ternary mixtures case, the ratio between the components was changed. The results were judged in light of the product size distribution at specified level of energy and the energy distribution between the mixture components. It was found that increasing the grinding energy level sharply affects the Gaudin-Schumann size modulus of the ground material whether was ground as single or a mixture. On contrary, the energy influence on the Gaudin-Schumann distribution modulus was minor. It was also found that the modified Charles equation for energy calculation (in mixture grinding) expresses very well the energy distribution between the mixture components. The energy distribution among the mixture components depends to a large extent on the hard component portion which enhances the grindability of the soft ones. For that reason quartz utilizes only 96% of its predicted energy in the mixture 1:2:1 at any applied level of grinding energy.
    Źródło:
    Inżynieria Mineralna; 2007, R. 8, nr 1, 1; 1-14
    1640-4920
    Pojawia się w:
    Inżynieria Mineralna
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Treatment of Hospital Wastewater Using Electrocoagulation Process – Analysis by Response Surface Methodology
    Autorzy:
    Salah Al-Shati, Ahmed
    Alabboodi, Khalid O.
    Shamkhi, Hassan A.
    Abd, Zahraa N.
    Emeen, Sara I. Mohammed
    Powiązania:
    https://bibliotekanauki.pl/articles/2202336.pdf
    Data publikacji:
    2023
    Wydawca:
    Polskie Towarzystwo Inżynierii Ekologicznej
    Tematy:
    electrocoagulation
    RSM
    response surface methodology
    COD removal
    Opis:
    Electrocoagulation (EC) can be defined a method utilized to remove pollutants from wastewater by applying an electric current to sacrificial electrodes. Many experimental variables like NaCl content (0–4 g/l), current density (5–25 mA/cm2), time (30–90 mins), and pH (4–10) that influence the removal efficiency regarding COD were considered. In the presented research, three distinct configurations related to electrodes, i.e. Al-Al, Fe-Al, and Fe-Fe, have been utilized to determine which was the most effective. RSM depending on BBD was utilized for optimizing various operational parameters with regard to HWW by use of EC. Maximum COD removal (97.9%) was reached at Fe-Al electrodes, NaCl (3.2 g/l), current density (24.7 mA/cm2), time (81.7 mins), and pH (7.4). COD removal (91.3%) was achieved at the Al-Al electrodes, NaCl (3.8 g/l), current density(23.5 mA/cm2), time-86.3 min, and Ph (7.7). At the Fe-Fe electrodes, the removal of COD (89.5%) was obtained at NaCl (2.3 g/l), current density (24.6 mA/cm2), pH 8.5, and time (86.9 min). This indicates that EC could remove pollutants from different types of wastewaters under many operating parameters and with arrangements of electrodes.
    Źródło:
    Journal of Ecological Engineering; 2023, 24, 1; 260--276
    2299-8993
    Pojawia się w:
    Journal of Ecological Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Collection of hospital wastewater data using deduplication approaches
    Autorzy:
    Khan, N. A.
    Sinha, G. R.
    Ahmed, S.
    Feshchenko, A.
    Changani, F.
    Qureshi, A.
    Mazhar, M. A.
    Neklonskyi, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1818511.pdf
    Data publikacji:
    2020
    Wydawca:
    Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
    Tematy:
    statistics
    hospital wastewater
    medical waste
    deduplication
    approaches
    servers
    statystyka
    ścieki szpitalne
    odpady medyczne
    deduplikacja
    podejścia
    serwery
    Opis:
    Purpose: This investigation aims to study the various approaches currently used to reduce the load on computer servers in order to better manage data on hospital wastewater treatment and solid waste generation. Design/methodology/approach: This manuscript investigates the taxonomies of deduplication procedures based on literature and other data sources, thereby presenting its classification and its challenges in detection. Findings: Based on the literature survey of deduplication techniques, the method of deduplication dispensed on cloud gadget devices has been found to be a promising research challenge. The gaps discussed include a reduction in storage space, bandwidth, type of disks used, and expenditure on energy usage and heat emissions when implementing these strategies. The art work on a scalable, robust, green and allocated approach to deduplication for a cloud gadget will remain of interest in destiny. Research limitations/implications: Considerable attention is focused on the deduplication due to efficient, extensive storage system. Practical implications: This research paper will be useful to identify deduplication techniques which are nowadays used in different hospital wastewater data collection systems and put significant proposals for further improvements in deduplication. Originality/value: This manuscript portrays a broader assessment of the available literature for data duplication along with the classification of different methods for the data storage used in the different level of storage of hospital wastewater data collection.
    Źródło:
    Archives of Materials Science and Engineering; 2020, 104, 1; 5--18
    1897-2764
    Pojawia się w:
    Archives of Materials Science and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Effect of Different Processing Methods on the Behavior of Minerals Content in Food Products
    Autorzy:
    Alshallash, Khalid S.
    Shahat, Mohamed
    Ibrahim, Mohamed I.
    Hegazy, Ahmed I.
    Hamdy, Ashraf E.
    Elnaggar, Ibrahim A.
    El-Wahed, Abd El-Wahed N. Abd
    Taha, Ibrahim M.
    Powiązania:
    https://bibliotekanauki.pl/articles/24201608.pdf
    Data publikacji:
    2023
    Wydawca:
    Polskie Towarzystwo Inżynierii Ekologicznej
    Tematy:
    mineral
    fruit
    processing
    canning
    dehydration
    stewing
    Opis:
    The goal of the current study was to determine the mineral content of different fruit varieties (Na, K, Ca, P, Mg, Fe, Zn, and Cu), as well as the effects of various processing methods (such as canning, drying, stewing, syrup process, and concentration of juices). All tested fruits that were subjected to various types of processing were exposed to a degree of mineral loss, varying from very little to high reduction. However, it still retains its nutritional value. All fig products have the greatest levels of most tested minerals, compared to other processed fruit products, particularly P and Fe. In turn, orange products supply higher quantities of Ca. On the other hand, apricot products have a comparable value of other minerals with those found in fig and orange products. Among canned juices, guava had the highest contents of Ca, P, and Fe, while mango scored the first juice as Mg and Zn supplying. Canned apricot halves contain the best amounts of K, Ca, P and Mg than the same products of apple and peach. Among jam products, fig jam has higher amounts of Na, Ca, P, Mg, and Fe than those found in other fruit jams. The concentration of fruit juices by vacuum-heating or dehydration of fruit produced higher mineral retentions than the fruit products that were processed by other techniques. The concentrated orange juice by vacuum-heating processing retained most of the minerals found in raw juice, also dried apricot sheet retained higher minerals than those retained in dehydrated whole apricot.
    Źródło:
    Journal of Ecological Engineering; 2023, 24, 3; 263--275
    2299-8993
    Pojawia się w:
    Journal of Ecological Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An assessment of unstimulated salivary flow rate, IgA and clinical oral dryness among active and passive smokers
    Autorzy:
    Nigar, Seeme
    Hassan, Sobia
    Maqsood, Afsheen
    Ahmed, Naseer
    Al-Askar, Mansour
    Mokeem, Sameer A.
    Alqutub, Montaser N.
    Aldahian, Nada
    AlSagob, Eman I.
    AlMubarak, Abdulrahman A.
    Vohra, Fahim
    Abduljabbar, Tariq
    Powiązania:
    https://bibliotekanauki.pl/articles/2085673.pdf
    Data publikacji:
    2022-02-15
    Wydawca:
    Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
    Tematy:
    IgA
    xerostomia
    passive smokers
    active smokers
    salivary flow rate
    oral dryness
    Opis:
    ObjectivesThe aim of this study was to assess the impact of smoking on the whole salivary flow rate (SFR), IgA levels and clinical oral dryness (COD) among active and passive smokers.Material and MethodsThe participants were categorized as active smokers (N = 54) or passive smokers (N = 163). Saliva was collected in tubes and placed in ice storage at –70°C. Salivary IgA levels were assessed in duplication using the enzyme linked immunosorbent assay (ELISA) method. Following the saliva sample collection, the subjects were assessed for COD using the COD score, SFR and caries. Chi-square test, the t-test and ANOVA were employed to compare the clinical impact of the smoking status associated with specific variables (smoking status, number of cigarettes, active caries, gender, age, COD score, IgA level and SFR). A p-value of <0.05 was considered significant.ResultsTwo hundred and seventeen subjects with the mean age of 32.86±6.30 years, with 145 males (66.8%) and 72 females (33.2%), were included in the study. Among the active smokers, 88.8% were males compared to 11.2% females. The active smokers had the mean age of 32.52 years, a COD score of 1.43, an IgA level of 1.39 g/l, and a SFR of 0.37 ml/min. Among the passive smokers, 59.5% were males and 40.5% were females, with the mean age of 32.97 years, a COD score of 0.87 g/l, an IgA level of 1.47, and a SFR of 0.42 ml/min. Active caries showed a positive correlation with the number of cigarettes, with significance in the >35 years age group (p < 0.05).ConclusionsThe study demonstrated significant differences in SFR, IgA and COD scores among the active and passive smokers. The number of cigarettes had a negative impact on saliva production, IgA levels, the oral health status, and the progression of caries with respect to age and gender. Smoking potentially leads to xerostomia associated with active caries.
    Źródło:
    International Journal of Occupational Medicine and Environmental Health; 2022, 35, 1; 39-51
    1232-1087
    1896-494X
    Pojawia się w:
    International Journal of Occupational Medicine and Environmental Health
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design of water supply networks for water transfer to the urban area Case study: Balikpapan city
    Autorzy:
    Huy, Dinh T.N.
    Dwijendra, Ngakan K.A.
    Poltarykhin, Andrey
    Suksatan, Wanich
    Nahi, Nooraldeen S.
    Mahmudiono, Trias
    Hai, Nguyen T.
    Kadhim, Mustafa M.
    Singh, Krishanveer
    Ahmed, Alim A.A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2174373.pdf
    Data publikacji:
    2022
    Wydawca:
    Instytut Technologiczno-Przyrodniczy
    Tematy:
    network design
    water distribution
    water shortage
    water supply network
    water transmission
    Opis:
    The growing population and the development of industries in all countries of the world have created a very important and complex issue for water supply to cities. Today, many parts of the world are facing the problem of water shortage and this problem cannot be easily solved. In addition to the proper use of water resources and preventing the loss of natural water, the establishment of regional water supply networks is effective in meeting the future needs of the people. A water distribution network (water supply network) is a set of interconnected pipelines used to transport and distribute water in a complex. In designing the water distribution network, factors such as the type of water distribution network, water pressure, water velocity, design flow, minimum pipe diameter, pipe material and many other factors should be considered. In this study, we have tried to design the water supply network of a part of Balikpapan city in Indonesia. The design method led to the determination of pressure values in the connection nodes, pipe diameters, flow rate and velocity in the pipes. All the existing criteria are considered in the design of the water supply network. Although this study has been implemented for a specific study area, it can be of great help to designers in designing the water supply network.
    Źródło:
    Journal of Water and Land Development; 2022, 54; 251--254
    1429-7426
    2083-4535
    Pojawia się w:
    Journal of Water and Land Development
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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