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[en] This paper focuses primarily on the thermal analysis of the steady, three-dimensional flow of CMC (sodium carboxymethyl cellulose) base fluid with Cu nanoparticles through the implantation plate of Riga in a porous Darcy–Forchheimer material with internal heat generation (absorption) effects. Thermophysical feature of CMC is taken into account with Al₂O₃ nanoparticle in it. Also, thermal radiation and convective boundary constraint are considered into account. Adequate transformations of the issue controlling formulas produce a system of nonlinear ordinary differential equations. The optimal homotopy analysis method is used for calculating the parameters values impacts. The expressions of local Nusselt number and skin friction coefficient are studied and debated. The physical influences of all emerging parameters are debated on graphically forms. The findings suggest that with higher values of Hartmann number, the skin friction in y-direction decreases on the contrary in the case of x-direction, while the Hartmann number increases the rate of heat transportation. Besides, the addition values of thermal radiation and Biot number enhance the rate of heat transport. Comparisons have been made with published literature, and an excellent agreement is clear. This underlines the importance of the study in potential medical and industrial cooling applications.

[en] The stepwise stability constants of (MHL) and (ML) complexes between transition (Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺, Mn²⁺, Cd²⁺) and lanthanide ions and 3,5-dinitro-2'-hydroxy benzanilide (DHBH) in 75% (v/v) dioxane-water at constant ionic strength (0.01 M KNO₃) were determined at different temperatures. The thermodynamic parameters for the proton-ligand and metal-ligand stability constants were obtained by the temperature coefficient method. The plot of thermodynamic parameters vs. ionic potential (Z²/r) of the lanthanide elements is not linear as expected from ionic theory. The obtained data support the interpretation of the expanded solvation sphere through the lanthanide series. Anomalies in chelating tendencies at gadolinium indicate a type of cross-over point at which solvent-metal and ligand-metal interaction may occur. Spectrophotometric studies were carried out for Cu²⁺ -, Ni²⁺ - and Co²⁺-DHB complexes. The solid complexes were isolated and characterized by elemental analysis, conductance, magnetic properties and infra-red spectra. (author)

[en] The present work concentrates on two-dimensional steady incompressible flow of a non-Newtonian cross nanofluid past a linear stretching/shrinking sheet with a magnetic field in Darcy-Forchheimer porous regime. The entropy theory with Arrhenius energy is incorporated into the study. The shooting method is employed to obtain numerical solutions of the transformed system of non-linear equations. The influence of the governing parameters on the non-dimensional velocity, temperature, micro-rotation, drag force, heat and mass transfer rates, rate of entropy generation, Bejan number, streamlines and finally isotherms are incorporated. The significant outcomes of the current investigation are that increment in suction parameter uplifts flow velocity, temperature and concentration while injection is petered out them. Bejan number augments due to increment in inertia coefficient while reduces due to magnetic strength and Eckert number. (paper)

[en] The aim of this paper is to analyse the functioning of the repair brigades in the process of failure removal in the water distribution subsystem using the mass service system (MSS). An example is presented using queuing model which takes into account notifications with various scheduling algorithms of failures occurring to the system. The functioning analysis of mass service system can be used in the optimization of the repair teams' actions and in the management of water supply companies. (authors)

[en] In nonlinear rotor-dynamics, techniques can take advantage of the periodic steady state behavior to predict quickly and accurately the mass unbalance response to a series of parameters, especially with the presence of certain nonlinearities which leads to nonlinear dynamics and complicated responses. The method proposed here calculates the response curve by combining Harmonic Balance Method (HBM), Alternating Frequency-Time (AFT) method and continuation. The singular points where a stability change often arises are detected with the sign change of the Jacobian determinant and then located through a penalty method that increases the solving equation system by a completing constraint. Tracking these points, which provides an efficient way to analyze parametrically the nonlinear behavior of a system, can be fulfilled, once again, by the continuation technique. (authors)

[en] Large Geographically-distributed and Hardware-based Networks (GHN) act as lifeline systems in providing energy, transportation, telecommunication, drinking water supply and sewage water treatment in any society. From the Civil Security (CS) point of view, it may also be a vector of failure propagation (cascade effects). Numerous disasters highlight the fact that GHN's service disruption extends the crisis duration (their restoration takes time) and the geographical area of the impacts because of dependencies between GHN. Several tools have been created to simulate dependencies between GHN. This article is a short illustrative catalog for CS Managers, providing various solutions, for modelling and simulating dependencies for/between different critical infrastructures. (authors)

[en] In this paper, nonlinear differential equation for a longitudinal fin (LF) heat transfer with thermal conductivity and heat generation that depends on temperature is solved numerically by employing Runge–Kutta technique of fourth-order (RK4) featuring shooting technique and analytically via a new modified analytical technique called Duan–Rach method. The physical model of the heat transfer was utilized to examine the influences of the thermogeometric parameters, heat transfer rate and variable thermal conductivity on the temperature profile and efficiency of LF. The obtained outcomes show that the temperature profile of fin, heat transfer and the efficiency of the fin are considerably impacted by the fin factor of thermogeometric. The analytical outcomes by a new efficient algorithm are compared with the numerical computations of the RK4 featuring shooting techniques and various available literature outcomes to achieve the precision of the proposed technique. Obtained results show obviously the fidelity of the suggested approach.

[en] The titanium glycolate colloids nanoparticle [TiO₂-EG]^NP is synthesized at pH ≅ 7, using solgel polymerization mothed. The polymerization method is accomplished in ethylene glycol solution as a soft template at 298 K. The polymerization technique to the production of [TiO₂-EG]^NP. The resulting [TiO₂-EG]^NP are investigated by various methods involving FTIR and XRD. The thickness of fabricated [TiO₂-EG]^NP thin film is (75 ± 5 nm) by using spin coater (SPIN150) with a speed rate of 2000 rpm/30 s. Numerical calculations are accomplished to study the heat transfer features of dilute TiO₂-EG nanofluid under diverse NP volume fraction and temperature values. An enhancement of 8.7% in thermal conductivity was observed with 0.2 vol% TiO₂-EG nanofluid. The overall heat transfer rate is observed which improves with increasing NP volume concentration and temperature. The experimental results, DFT, and numerical calculations are noticed reasonably consistently. The coolant surface heat transfer rate has been increased by approximately 24% by 2% TiO₂-EG nanofluid at the same temperature level, which could be attributable to enhanced thermal conductivity and improved free convection due to a reduction in viscosity. Our results show that the nanofluid TiO₂-EG provides liquid coolants but is also more heat-specific and therefore suitable for energy management.

Graphic abstract

The electron density of [TiO₂-EG]^NP and TEM image of TiO₂ particles powder.

[en] In this paper, a general framework for the modelling of physical phenomena with stochastic dynamical systems switched by jump Markov processes is given. A methodology of the associated estimation procedures is provided. A particular attention is paid to the estimation of the underlying jump process, which is not observable. As an application, a stochastic model is proposed for the fatigue crack growth problem. The estimation of the model parameters is made on a real crack growth data set. We are thus able to simulate some crack growth paths which are used for reliability analysis through Monte Carlo techniques