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 Showing 601 - 800 of 1205 Journals sorted alphabetically International Journal of Quality Assurance in Engineering and Technology Education       (Followers: 3) International Journal of Quality Engineering and Technology       (Followers: 4) International Journal of Quantum Information       (Followers: 6) International Journal of Rapid Manufacturing       (Followers: 3) International Journal of Recent Contributions from Engineering, Science & IT International Journal of Reliability, Quality and Safety Engineering       (Followers: 14) International Journal of Renewable Energy Technology       (Followers: 8) International Journal of Robust and Nonlinear Control       (Followers: 10) International Journal of Science and Innovative Technology International Journal of Science Engineering and Advance Technology International Journal of Sediment Research       (Followers: 2) International Journal of Self-Propagating High-Temperature Synthesis International Journal of Service Science, 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and Science Iranian Journal of Optimization       (Followers: 2) Iranian Journal of Science and Technology, Transactions A : Science IRBM News Ironmaking & Steelmaking       (Followers: 4) ISA Transactions ISSS Journal of Micro and Smart Systems       (Followers: 3) IT Professional       (Followers: 24) Iteckne J-ENSITEC : Journal Of Engineering and Sustainable Technology       (Followers: 4) Johnson Matthey Technology Review Journal of Advanced College of Engineering and Management Journal of Advanced Joining Processes Journal of Advanced Manufacturing Systems       (Followers: 5) Journal of Aerodynamics       (Followers: 27) Journal of Aerosol Science       (Followers: 7) Journal of Aerospace Engineering       (Followers: 66) Journal of Alloys and Compounds       (Followers: 16) Journal of Analytical and Applied Pyrolysis       (Followers: 5) Journal of Analytical Science & Technology       (Followers: 4) Journal of Analytical Sciences, Methods and Instrumentation       (Followers: 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Similar Journals
 Iranian Journal of Science and Technology, Transactions A : ScienceNumber of Followers: 0      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1028-6276 - ISSN (Online) 2364-1819 Published by Springer-Verlag  [2469 journals]
• Quantum Effects on Modulational Amplification Characteristics of
Semiconductor Magneto-Plasmas

Abstract: Using quantum hydrodynamic model, quantum effects (via Bohm potential) on modulational amplification characteristics of semiconductor magneto-plasmas are investigated. Expressions are obtained for the threshold pump amplitude and the growth rate of modulated beam with including and excluding quantum effects. Numerical analysis is performed for n-InSb/CO2 laser system. The dependence of the threshold pump amplitude and the growth rate of modulated beam on wave number, applied magnetic field, and plasma carrier concentration are explored. The lowering in threshold pump amplitude and enhancement of growth rate of modulated beam are observed by incorporating the quantum effects. The analysis provides detailed information of quantum effects on semiconductor magneto-plasmas and establishes the technological potentiality of semiconductor magneto-plasmas as the hosts for fabrication of efficient optical modulators.
PubDate: 2022-05-16

• Assessment of Annual Effective Dose and Excess Lifetime Cancer Risk in
Grain Samples Collected from Kerbala Governorate, Iraq

Abstract: Natural radioactivity for gamma emitters (specific activity 238U, 232Th, and 40K) using NaI(Tl) detectors and alpha emitters (concentrations of 222Rn, 226Ra, and 238U) using CR-39 detector was determined in some grains samples that collected from Kerbala Governorate markets, Iraq. Also, annual effective dose and some radiological parameters due to gamma and alpha emitters to assess the health risk were calculated. The results show that the average value of specific activity with (S.E) for 238U was 6.61 ± 0.91 Bq/kg, for 232Th was 3.07 ± 0.22 Bq/kg, and for 40K was 227.59 ± 32.34 Bq/kg. while the average value of alpha emitters concentrations for 222Rn, 226Ra, and 238U were 3.99 ± 1.13 Bq/m3, 4.69 ± 1.28 mBq/kg and 0.072 ± 0.019 Bq/kg respectively. The results of average total annual effective dose associated with the exposure due to gamma and alpha emitted from ingestion grain samples in the present study were 0.139 ± 0.013 mSv/y and 0.172 ± 0.047 µSv/y, respectively. The grain samples in present study having normal levels of radiological hazard due to natural gamma and alpha emitters within global limit. Therefore, it can be concluded that a grain sample does not pose any kind of health hazards or radiological effects to the inhabitant of the study area.
PubDate: 2022-05-14

• Global Dynamics of a Diffusive Two-Strain Epidemic Model with Non-Monotone
Incidence Rate

Abstract: In this article, we investigate a diffusive two-strain epidemic model with non-monotone incidence rate and virus mutation. The positivity, existence and uniform boundedness of the solutions of the model system are studied. It is found that the system has three equilibrium points, namely the infection-free equilibrium point, the strain-2 endemic equilibrium point and both the strain-1 and strain-2 endemic equilibrium points. The global asymptotic stability analysis of the diffusive model system near all the equilibrium points is carried out by constructing appropriate Lyapunov functional. It is found that the system has no strain-1 endemic equilibrium point possibly due to the virus mutation. So, in this type of diseases, the infection due to strain-1 cannot be persistent in the community.
PubDate: 2022-05-13

• Bohr Radius for Some Classes of Harmonic Mappings

Abstract: In this note, we introduce a general class of sense-preserving harmonic mappings defined as follows: \begin{aligned} \mathcal {B}_{\mathcal {H}}^{0}(M):= \{f=h+\bar{g}: \sum _{m=2}^{\infty }(\gamma _m a_m +\delta _m b_m )\le M, \; M>0 \}, \end{aligned} where $$h(z)=z+\sum _{m=2}^{\infty }a_mz^m$$ , $$g(z)=\sum _{m=2}^{\infty }b_m z^m$$ are analytic functions in $$\mathbb {D}:=\{z\in \mathbb {C}: z \le 1 \}$$ and \begin{aligned} \gamma _m,\; \delta _m \ge \alpha _2:=\min \{\gamma _2, \delta _2\}>0, \end{aligned} for all $$m\ge 2$$ . We obtain Growth Theorem, Covering Theorem, and derive the Bohr radius for the class $$\mathcal {B}_{\mathcal {H}}^{0}(M)$$ . As an application of our results, we obtain the Bohr radius for many classes of harmonic univalent functions and some classes of univalent functions.
PubDate: 2022-05-13

• Evaluation of Natural Radionuclides in Samples of Plant Fertilizers Used
in Iraq and Radiation Hazard Indicators

Abstract: In this study, the specific activity was identified in 12 fertilizer samples using a gamma spectroscopy, and the results showed that the average specific activity of natural radionuclides (226Ra, 232Th, 40 K) was 36.24 ± 0.767 Bq/kg, 55.40 ± 0.973 Bq/kg, and 202.87 ± 5.062 Bq/kg, respectively, where the average specific activity of 226Ra and 232Th exceeded the globally recommended limits, while the average specific activity of 40 K was within the internationally recommended limits by UNSCEAR. The radium equivalent Raeq, absorbed dose rate in air $${D}_{\gamma }$$ , annual effective dose equivalent for indoor and outdoor exposure (AEDEindoor and AEDEoutdoor), excess lifetime cancer risk ELCR, internal and external hazard indicators (Hin and Hex) and gamma representative level index were calculated. The results of most samples were within the global average recommended by UNSCEAR, so it is safe to consume and does not pose a threat to the general public.
PubDate: 2022-05-11

• Point Vortex Dynamics for the 2D Boussinesq Equations Over the Tropics

Abstract: The aim of this paper is to find some vortex solutions of finite core size for plane Boussinesq equations in a weighted subspace of $$L^2(\mathbb {R}^2)$$ . Here, the solution of the vorticity and temperature equations are separated into $$N$$ components and derive separate evolution equations for each component. Next, the solutions are expanded into series of Hermite eigenfunctions. Hence, it is obtained the coefficients of the series and a set of $$2n$$ PDEs which govern the evolution of the vorticity of each vortex structure and a set of $$4n$$ ODEs governing the motion of the centers of each vortex structure.
PubDate: 2022-05-10

• Fractional Derivatives with Variable Memory

Abstract: Recently, fractional derivatives (FDs) and fractional differential equations are extensively used in modeling of most dynamic processes which generally involve memory factors. Normally, the dynamic models involving full memory effect can be solved with the help of global fractional derivatives, whereas those involves with local memory effect can be solved by using only fractional derivatives with short memory. The prime objective of this work is to define new fractional derivatives of Riemann–Liouville and Caputo types, which can be used for both short and global memory effects. Some general and dynamic properties of the proposed differential operators in comparison to existing formulas of FDs are discussed.
PubDate: 2022-05-10

• Set-Valued Control to COVID-19 Spread with Treatment and Limitation of
Vaccination Resources

Abstract: In this paper, we consider an SEIR model that describes the dynamics of the COVID-19 pandemic. Subject to this model with vaccination and treatment as controls, we formulate a control problem that aims to reduce the number of infectious individuals to zero. The novelty of this work consists of considering a more realistic control problem by adding mixed constraints to take into account the limited vaccines supply. Furthermore, to solve this problem, we use a set-valued approach combining a Lyapunov function defined in the sense of viability theory with some results from the set-valued analysis. The expressions of the control variables are given via continuous selection of an adequately designed feedback map. The main result of our study shows that even though there are limits of vaccination resources, the combination of treatment and vaccination strategies can significantly reduce the number of exposed and infectious individuals. Some numerical simulations are proposed to show the efficiency of our set-valued approach and to validate our theoretical results.
PubDate: 2022-05-08

• Activity and Stability of Dextranase from New Penicillium Funiculosum
TFZ.91: Optimization by Response Surface Methods

Abstract: With the aid of experimental design, in this study, we have investigated the activity and stability of dextranase, an important extracellular inducible enzyme that specifically hydrolyzes the α-1,6 glycosidic linkages of dextran, leading to the formation of D-glucose and shorter oligosaccharides. The experimental design results showed the significant individual as well as interaction effects of the tested parameters affecting the dextranase activity and stability. The numerical optimization study suggested that the desired maximum activity and stability of dextranase can be obtained at temperature 40 °C and pH value 6.5. In addition, stability tests showed that dextranase was stable, without compromising its activity, up to 55 °C and in pH range 5–8. Considering the influence of investigated reagents on dextranase activity, the results revealed a pronounced activating effect of glycerol and sucrose, especially with increasing their concentration, with the highest activity detected in the presence of sucrose at 10 mM (129%). Regarding the influence of added metal ions, the higher dextranase activity is recorded in the presence of Ag+, Ca2+, K+, Mg2+, and Si2+ ions, from which the Ca2+ ions were the most effective, and in their presence, at 10 mM the activity of dextranase was 119%.
PubDate: 2022-05-06

• Nuclear Structure of Samarium Isotopes Using Skyrme and Gogny
Hartree–Fock–Bogoliubov Method

Abstract: The ground-state properties of the Samarium 123−208Sm (Z = 62) Isotopes were investigated in the framework of the Hartree–Fock–Bogoliubov (HFB) method based on different types of the Skyrme and Gogny effective nucleon–nucleon interactions. In this work, we display the calculated results, including the binding energy per particle (B.E/A), quadrupole deformation parameter (β2), potential energy curves, proton quadrupole moment (Qp), neutron pairing gap, double neutron separation energy (S2n) and single-particle levels. Our calculation results have been compared with the experimental measurements, the predictions of Finite-Range-Droplet-Model (FRDM), HFB-Gogny predictions, and Relativistic Mean-Field (RMF) theory. Good agreements were obtained. Our calculated values of B.E/A, β2, Qp and S2n for the investigated isotopes varied approximately: from 6.8 to 8.0 MeV, from − 0.2 to 0.4, from − 4.0 to 8.0 b and from − 3 to 27 MeV, respectively. Present investigations indicate the maximum deformation of the Sm isotopes at 62 < N > 74 and 89 < N > 109 up to β2 ≈ 0.4, where the most pronounced prolate deformation minimum is located between β2 = 0.2 and 0.3.
PubDate: 2022-05-06

• Nalbuphine Pretreatment Improves Myocardial Cell Viability Induced by H/R
Through TLR4/NLRP3-Mediated Pyroptosis

Abstract: Abstract Myocardial ischemic–reperfusion injury (MIRI) has been the nonnegligible obstacle for the treatment of myocardial infarction that is the dominating cause of morbidity and mortality in cardiovascular diseases around the world. To explore the potential therapeutic drugs and the underlying molecular mechanisms of the MIRI, hypoxia/reoxygenation (H/R) was used to treat H9c2 cardiomyocyte cells to simulate MIRI. The cell viability of H9c2 cardiomyocyte cells was a dose-dependent reduction with nalbuphine, and the maximum non-toxic concentration of nalbuphine was 200 μM. H/R treatment significantly decreased cell viability and increased the rate of pyroptosis and pyroptosis-related proteins levels of H9c2 cardiomyocyte cells, which was prominently reversed with 200 μM nalbuphine pretreatment. Moreover, TLR4 overexpression prominently reduced the cell viability and enhanced the rate of pyroptosis and pyroptosis-related proteins levels of H9c2 cardiomyocyte cells based on the pretreatment of nalbuphine. Therefore, nalbuphine pretreatment improved myocardial cell viability induced by H/R through TLR4/NLRP3-mediated pyroptosis.
PubDate: 2022-04-27

• A Method for Cancer Genomics Feature Selection Based on LASSO-RFE

Abstract: Abstract A more efficient feature selection method was developed to screen genes corresponding to specific cancers to further investigate their pathogenesis. The LASSO-RFE model, a last absolute shrinkage and selection operator (LASSO) classifier based on the idea of recursive feature elimination (RFE), was constructed. To verify the efficiency of the proposed algorithm, performance tests were conducted by using four kinds of gene expression RNA sequences publicly available in The Cancer Genome Atlas (TCGA). The numerical experiments were used to illustrate that the proposed LASSO-RFE enables a higher accuracy of the classification prediction model and a clearer biological interpretability of the selected gene features compared with three typical feature selection algorithms. The experimental results showed that LASSO-RFE effectively reduced tens of thousands of features in the original data to three dimensions and provided better performance for the classification model than mutual information, L1-SVM and tree-based selection method. This model retains the ability of the common LASSO algorithm to filter and remove redundant and irrelevant features, and enhances the biological interpretability according to RFE, which was compared with the traditional feature reduction methods. In this paper, only a limited number of data cases have been validated, and the application of LASSO-RFE with more recent data remains to be further investigated.
PubDate: 2022-04-20

• An Efficient Alternative Kernel of Gaussian Radial Basis Function for
Solving Nonlinear Integro-Differential Equations

Abstract: Abstract This paper focuses on improving radial basis function (RBF) method for solving nonlinear Volterra–Fredholm integro-differential equations. The RBF method is one of the most important numerical techniques for approximating the solution of problems and interpolating scattered data in any dimensions. Infinitely smooth RBFs such as Gaussians (GA) have the spectral convergence rate. These kernels depend on an auxiliary parameter, called shape parameter that plays a significant role to specify the accuracy of RBF method. When this parameter is close to zero, we achieve the highest accuracy, here the standard RBF interpolant matrix becomes severely ill-conditioned. To overcome this problem, we use a stable alternative base made on the eigenfunction expansion with the help of the properties of the orthogonal Hermite polynomials for GA-RBFs. This idea produces a stable cardinal interpolation function that lacks eigenvalues as the factors of the ill-conditioning of the interpolation matrix. We generalize the upper bound of Volterra integro-differential from x to a function in terms of x with specific conditions. By applying this approach and the Legendre–Gauss–Lobatto quadrature formula, the solution of problem under study is reduced to the solution of a nonlinear system of algebraic equations. We also examine the effect of the number of Legendre–Gauss–Lobatto nodes on the accuracy of the calculations. Furthermore, we find an upper bound for the error function. Several numerical experiments indicate that the present method is more accurate and stable in comparison with the standard GA-RBFs and some other methods.
PubDate: 2022-04-16

• A Novel Two-Particle Steady-State Wave Equation

Abstract: Abstract There is not only the Coulomb force in the orbiting motion between two charged particles, but also a certain magnetic moment coupling interaction. Therefore, according to the macroscopic phenomenon of dipoles, this paper revises the relevant terms of the two-particle stationary Schrödinger equation. The correction in the hydrogen atom and U91+ ion (hydrogen) calculation of hyperfine structure has high calculation precision, such as lamb shift U91+ ions and the theoretical value of quantum electrodynamics basic same. In terms of hyperfine splitting, the developed series is more than the number of quantum electrodynamics and puts forward the concept of the electron orbital tilt angle for the first time. For example, the orbital inclination of hydrogen atom is approximately 0.000069207 radians, and that of U ion is approximately 0.000041427 radians. The results showed that it is because of the existence of this orbital skew that the ground-state electrons will move in a spiral asymptote way, rather than in a closed circular trajectory. This paper also calculates the interaction force between the Sun and Mercury. The calculated result is a third-order tiny quantity more than Newtonian mechanics, which is better than the calculation method of the stationary Schrödinger equation.
PubDate: 2022-04-16

• Boubaker Matrix Polynomials and Nonlinear Volterra-Fredholm
Integro-differential Equations

Abstract: Abstract In this paper, a new scheme for the formulation of operational matrix form of the integration, differentiation, and approximate functions in any arbitrary interval which will be used in the Galerkin method is presented. There are so many methods to obtain operational matrices for Chebyshev, Legendre, Bernstein, Bessel, etc., polynomials. Our aim is to determine the exact operational matrices for the Boubaker polynomials. This method transforms the nonlinear Volterra-Fredholm integro-differential equations into a system of nonlinear algebraic equations which will be solved easily by the Galerkin procedure. Also, an error estimate and numerical analysis of the proposed method are shown through some theorems. Moreover, the existence and the uniqueness of the solution in this scheme have been proved. To illustrate the efficiency and capability of the method, some examples are presented and their results are compared with the results of some other well-known methods. In addition, an application of this algorithm to the population model is given. The outcome of these examples and their CPU times confirm the capability and validity of this algorithm.
PubDate: 2022-04-01

• A Numerical Approach for Stochastic Switched Polynomial Optimal Control
and Approximating Control Lyapunov Functions

Abstract: Abstract In this paper, we present an approach based on sum-of-squares (S.O.S) techniques for searching the solution of stochastic switched nonlinear optimal control problems with polynomial data, where the number of switches and the distribution of the switching signal are not pre-assigned. The problem is converted to an embedded polynomial form using a new control variable that is responsible for controlling the switching policy. Using expected occupation measures, the embedded problem is relaxed as a primal infinite-dimensional linear programming problem whose dual leads to a hierarchy of S.O.S problems, through which we approximate both optimal feedback switching signal and continuous input. Furthermore, for a particular case that the subsystems and the cost functions are affine and quadratic in control input, respectively, the approximating polynomials given by solving the S.O.S problems can be considered as polynomial stochastic control Lyapunov functions of the switched systems.
PubDate: 2022-04-01

• Uniform Convergent Solution of Singularly Perturbed Parabolic Differential
Equations with General Temporal-Lag

Abstract: Abstract In this paper, we presented a parameter uniform B-spline collocation nonstandard finite difference scheme for a class of singularly perturbed parabolic one-dimensional convection–diffusion problems with a time delay on a uniform mesh. When the delay parameter is smaller than the perturbation parameter, the delayed term is expanded in Taylor series and a B-spline collocation tridiagonal nonstandard finite difference scheme is developed. Here, the proposed finite difference scheme is unconditionally stable and is first-order convergent in the temporal direction and second-order accurate in the spatial direction. When the delay parameter is larger than the perturbation parameter, a special type of mesh is used for the temporal variable so that the delay lie on the nodal points and B-spline collocation nonstandard finite difference scheme is developed. The scheme is also unconditionally stable and is first-order convergent in the temporal direction and second-order accurate in the spatial direction. We carried out numerical simulations to verify the theoretical results.
PubDate: 2022-04-01

• Some Points on c-K-g-Frames and Their Duals

Abstract: Abstract In this paper, we study some new properties of c-K-g-frames in a Hilbert space H. We study duals of c-K-g-frames and give some characterizations of c-K-g-frames and their duals. Also, we verify the relationships between c-K-g-frames and atomic cg-systems. Precisely, we show that these two concepts are equivalent. Finally, we find some new atomic cg-systems from given ones.
PubDate: 2022-04-01

• Comparison of Two Hybrid Functions for Numerical Solution of Nonlinear
Mixed Partial Integro-Differential Equations

Abstract: Abstract In the present paper, two methods have been introduced for solving two-dimensional nonlinear mixed Volterra–Fredholm partial integro-differential equations with initial conditions. Hybrid two-dimensional Taylor polynomials and block pulse functions and operational matrices of integration and derivative have been proposed for numerical approximation. Hybrid two-dimensional Legendre polynomials and block pulse functions have been also utilized for comparison of obtained solutions. These operational matrices have been applied for two methods to reduce the given system of algebraic equations. The error analysis and convergence analysis and some numerical results are provided to describe the efficiency and validity of the schemes through the comparison errors. Several figures are plotted to establish the error analysis of the approaches presented.
PubDate: 2022-03-23

• Conduction and Resistive Switching in Dropcast CdTe/CdSe Core-Shell
Quantum Dots Embedded Chitosan Composite

Abstract: Abstract We report on conduction and resistive switching in devices consisting of chitosan dispersed with CdTe/CdSe core-shell quantum dots (QDs) active layers sandwiched between silver (Ag) and indium doped tin oxide (ITO) electrodes. Active layers consisting of $$0.96\, \mathrm{wt}\%$$ , $$0.48\, \mathrm{wt}\%$$ , $$0.32\, \mathrm{wt}\%$$ and $$0.24\, \mathrm{wt}\%$$ QDs to chitosan were deposited on the ITO surface using the cost-free drop cast method. The electrical study performed on all devices revealed ‘O-type’ memory behaviour with OFF-state current conduction mechanism attributed to hopping mechanism. On the other hand, the ON-state current in each device followed a unique mechanism, such that Ohmic behaviour was observed for the device with $$0.96\, \mathrm{wt}\%$$ , while linear then hopping, space-charge limited, and lastly, hopping conductions mechanisms were attributed to devices with $$0.48\, \mathrm{wt}\%$$ , $$0.32\, \mathrm{wt}\%$$ and $$0.24\, \mathrm{wt}\%$$ , respectively. Our results show that these devices’ memory behaviour and conduction can be exploited by controlling the amount of CdTe/CdSe in the chitosan medium.
PubDate: 2022-03-14

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