This study examines the relationship between economic growth, renewable energy consumption, and carbon emissions in Iran between 1975-2017, and the bounds testing approach to cointegration and the ...asymmetric method was used in this study. The results reveal that in the long run increase in renewable energy consumption and CO.sub.2 emissions causes an increase in real GDP per capita. Meanwhile, the decrease in renewable energy has the same effect, but GDP per capita reacts more strongly to the rise in renewable energy than the decline. Besides, in the long run, a reduction of CO.sub.2 emissions has an insignificant impact on GDP per capita. Furthermore, the results from asymmetric tests suggest that reducing CO.sub.2 emissions and renewable energy consumption do not have an essential role in decreasing growth in the short run. In contrast, an increase in renewable energy consumption and CO.sub.2 emissions do contribute to boosting the growth. These results may be attributable to the less renewable energy in the energy portfolio of Iran. Additionally, the coefficients on capital and labor are statistically significant, and we discuss the economic implications of the results and propose specific policy recommendations.
This study discusses the flow of hybrid nanofluid over an infinite disk in a Darcy-Forchheimer permeable medium with variable thermal conductivity and viscosity. The objective of the current ...theoretical investigation is to identify the thermal energy characteristics of the nanomaterial flow resulting from thermo-solutal Marangoni convection on a disc surface. By including the impacts of activation energy, heat source, thermophoretic particle deposition and microorganisms the proposed mathematical model becomes more novel. The Cattaneo-Christov mass and heat flux law is taken into account when examining the features of mass and heat transmission rather than the traditional Fourier and Fick heat and mass flux law. MoS
and Ag nanoparticles are dispersed in the base fluid water to synthesize the hybrid nanofluid. PDEs are transformed to ODEs by using similarity transformations. The RKF-45th order shooting method is used to solve the equations. With the use of appropriate graphs, the effects of a number of non-dimensional parameters on velocity, concentration, microorganism, and temperature fields are addressed. The local Nusselt number, density of motile microorganisms and Sherwood number are calculated numerically and graphically to derive correlations in terms of the relevant key parameters. The findings show that as we increase the Marangoni convection parameter, skin friction, local density of motile microorganisms, Sherwood number, velocity, temperature and microorganisms profiles increase, whereas Nusselt number and concentration profile exhibit an opposite behavior. The fluid velocity is reduced as a result of enhancing the Forchheimer parameter and Darcy parameter.
In this paper, we have explored the effects of dissipation on the dynamics of charged bulk viscous collapsing cylindrical source which allows the out-flow of heat flux in the form of radiations. The ...Misner–Sharp formalism has been implemented to drive the dynamical equation in terms of proper time and radial derivatives. We have investigated the effects of charge and bulk viscosity on the dynamics of collapsing cylinder. To determine the effects of radial heat flux, we have formulated the heat transport equations in the context of Müller–Israel–Stewart theory by assuming that thermodynamics viscous/heat coupling coefficients can be neglected within some approximations. In our discussion, we have introduced the viscosity by the standard (non-causal) thermodynamics approach. The dynamical equations have been coupled with the heat transport equation; the consequences of the resulting coupled heat equation have been analyzed in detail.
Summary
The use of intra‐operative Doppler oesophageal probes provides continuous monitoring of cardiac output. This enables optimisation of intravascular volume and tissue perfusion in major ...abdominal surgery, which is thought to reduce postoperative complications and shorten hospital stay. Medline and EMBASE were searched using the standard methodology of the Cochrane collaboration for trials that compared oesophageal Doppler monitoring with conventional clinical parameters for fluid replacement in patients undergoing major elective abdominal surgery. Data from randomised controlled trials were entered and analysed in Meta‐view in Rev‐Man 4.2 (Nordic, Denmark). We included five studies that recruited 420 patients undergoing major abdominal surgery who were randomly allocated to receive either intravenous fluid treatment guided by monitoring ventricular filling using oesophageal Doppler monitor or fluid administration according to conventional parameters. Pooled analysis showed a reduced hospital stay in the intervention group. Overall, there were fewer complications and ICU admissions, and less requirement for inotropes in the intervention group. Return of normal gastro‐intestinal function was also significantly faster in the intervention group. Oesophageal Doppler use for monitoring and optimisation of flow‐related haemodynamic variables improves short‐term outcome in patients undergoing major abdominal surgery.
This paper is about the
n
+
2
-dimensional gravitational contraction of an inhomogeneous fluid without heat flux in the framework of a
f
(
R
) metric theory of gravity. Matching conditions for two ...regions of a star are derived by using the Darmois junction conditions. For the analytic solution of the equations of motion in modified
f
(
R
) theory of gravity, we have taken the scalar curvature constant. Hence the final result of gravitational collapse in this framework is the existence of black hole and cosmological horizons, and both of these form earlier than the singularity. It is shown that a constant curvature term
f
(
R
0
)
(
R
0
is the constant scalar curvature) slows down the collapsing process.
Copper is primarily used in many industrial processes, but like many other metals, it suffers from corrosion damage. Polymers are not only one of the effective corrosion inhibitors but also are ...environmentally friendly agents in doing so. Hence, in this paper, the efficacy of two polyelectrolyte polymers, namely poly(acrylic acid) (PAA) and polyacrylamide (PAM), as corrosion inhibitors for copper in molar nitric acid medium was explored. Chemical, electrochemical, and microscopic tools were employed in this investigation. The weight-loss study revealed that the computed inhibition efficiencies (% IEs) of both PAA and PAM increased with their concentrations but diminished with increasing HNO
concentration and temperature. The results revealed that, at similar concentrations, the values of % IEs of PAM are slightly higher than those recorded for PAA, where these values at 298 K reached 88% and 84% in the presence of a 250 mg/L of PAM and PAA, respectively. The prominent IE% values for the tested polymers are due to their strong adsorption on the Cu surface and follow the Langmuir adsorption isoform. Thermodynamic and kinetic parameters were also calculated and discussed. The kinetics of corrosion inhibition by PAA and PAM showed a negative first-order process. The results showed also that the used polymers played as mixed-kind inhibitors with anodic priority. The mechanisms of copper corrosion in nitric acid medium and its inhibition by the tested polymers were discussed. DFT calculations and molecular dynamic (MD) modelling were used to investigate the effect of PAA and PAM molecular configuration on their anti-corrosion behavior. The results indicated that the experimental and computational study are highly consistent.
The full-potential linear-augmented-plane-waves plus local-orbitals (FP-LAPW+lo) method has been employed for investigation of half-metallic ferromagnetism in Cr-doped ordered zinc-blende MgSe and ...MgTe semiconductors. Calculations of exchange and correlation (XC) effects have been carried out using generalized gradient approximation (GGA) and orbital independent modified Becke–Johnson potential coupled with local (spin) density approximation (mBJLDA). The thermodynamic stability of the compounds and their preferred magnetic orders have been analyzed in terms of the heat of formation and minimum total energy difference in ferromagnetic (FM) and anti-ferromagnetic (AFM) ordering, respectively. Calculated electronic properties reveal that the Cr-doping induces ferromagnetism in MgSe and MgTe which gives rise to a half-metallic (HM) gap at Fermi level (EF). Further, the electronic band structure is discussed in terms of s (p)–d exchange constants that are consistent with typical magneto-optical experiment and the behavior of charge spin densities is presented for understanding the bonding nature. Our results demonstrate that the higher effective potential for the spin-down case is responsible for p–d exchange splitting. Total magnetic moment (mainly due to Cr-d states) of these compounds is 4µB. Importantly, the electronic properties and HM gap obtained using mBJLDA show remarkable improvement as compared to the results obtained using standard GGA functional.
•Spin effect theoretical study on Cr-doped MgSe and MgTe is performed.•Half-metallic ferromagnetism in CrxMg1−xSe and CrxMg1−xTe is established.•Results of WC-GGA and mBJLDA are compared for performance.•HM gaps for CrxMg1−xSe and CrxMg1−xTe show nonlinear variation with x.•Important values of exchange splitting/constants and moments are reported.
The dynamic behavior of concrete is studied experimentally by testing annular and solid concrete specimens using split Hopkinson pressure bar (SHPB). The dynamic increase factor (DIF) of annular ...samples is relatively lower than the DIF of solid samples. The dynamic behavior of concrete seems to be independent of the quasi-static strength of concrete. The mode of failure of concrete was a typical ductile failure at high strain-rates and brittle at low strain-rates. No significant influence of strain-rate on the initial elastic modulus of concrete was observed. An empirical equation is proposed for the estimation of DIF of concrete based on the experiments. A model is developed for the prediction of stress–strain curve of concrete under dynamic loading which shows good agreement with the experiments.
The complex permittivity (
ε′–
jε″), complex permeability (μ′–
jμ″) and microwave absorption properties of ferrite–polymer composites prepared with different ferrite ratios of 50%, 60%, 70% and 80% ...in polyurethane (PU) matrix have been investigated in X-band (8.2–12.4
GHz) frequency range. The M-type hexaferrite composition BaCo
+2
0.9Fe
+2
0.05Si
+4
0.95Fe
+3
10.1O
19 was prepared by solid-state reaction technique, whereas commercial PU was used to prepare the composites. At higher GHz frequencies, ferrite's permeabilities are drastically reduced, however, the forced conversion of Fe
+3 to Fe
+2 ions that involves electron hopping, could have increased the dielectric losses in the chosen composition. We have measured complex permittivity and permeability using a vector network analyzer (HP/Agilent model PNA E8364B) and software module 85071. All the parameters
ε′,
ε″,
μ′ and
μ″ are found to increase with increased ferrite contents. Measured values of these parameters were used to determine the reflection loss at various sample thicknesses, based on a model of a single-layered plane wave absorber backed by a perfect conductor. The composite with 80% ferrite content has shown a minimum reflection loss of −24.5
dB (>99% power absorption) at 12
GHz with the −20
dB bandwidth over the extended frequency range of 11–13
GHz for an absorber thickness of 1.6
mm. The prepared composites can fruitfully be utilized for suppression of electromagnetic interference (EMI) and reduction of radar signatures (stealth technology).
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