Viscous System Research Articles

Beyond contribution of ionic liquids in nanostructuring polyaniline morphology; its effect on the properties of the polymerization medium

In the present work, the focus has been shifted to the relationship between the PANI morphology and the physicochemical properties, controlled by the amount of added ionic liquids, of the polymerization medium instead of focusing on the structure of the ionic liquids as used to be in the litterature. For that reason, PANI has been synthesized in different weight ratio of [Pyrr][PTS]/water following the standard experimental process. The addition of [Pyrr][PTS] into the polymerization medium controls the morphology of PANI without affecting its structure. Moreover, [Pyrr][PTS] promotes a viscous reaction system without the need of an external source. The viscosity of the polymerization system restricts the diffusion of species that leads to the predominance of the homogeneous nucleation mode during the course of polymerization and, thus, nanostructuring of PANI morphology. As for the ionic conductivity, it reflects the mobility of the ions of the polymerization medium and, thus, the way of its interference with the formed PANI that affects the arrangement and the shape of formed PANI fibers. This relationship between PANI morphology and the physicochemical properties, adjusted by adding ionic liquids, of the polymerization medium is prelaminar and promising. The effect of the ionic liquids on the viscosity as well as on the mobility of the polymerization medium have to be taken into consideration to choose the ionic liquids, which lead to the PANI with desired morphology.

Seismic performance of structure equipped with a new rubber bracing damper system

Nowadays, vibration energy absorption devices are widely implemented in many buildings subjected to severe vibration due to natural hazards, such as earthquakes, strong winds, and typhoons. Recently, viscous dampers have been commonly used in many structures as the most conventional damper type. However, the high maintenance cost resulting from oil leakage from cylinder seals has prompted researchers to seek an alternative system to viscous damper systems. Therefore, the main aim of this research is to develop a new rubber bracing damper (RBD) system by implementing high damping rubber material as a viscoelastic material to be installed in framed structures as diagonal bracing members. This will help dissipate vibration effects on the structure. To achieve this, the initial design for the RBD device has been developed, and finite-element simulation has been conducted to evaluate the behavior of the proposed RBD under various dynamic loading conditions. To define the viscoelastic material properties in finite-element modeling, high damping rubber material has been produced and experimentally tested to determine the numerical model of the material. Subsequently, the test data were utilized to develop the analytical model of the RBD device, and its performance was evaluated by applying cyclic loads and conducting nonlinear analysis. Furthermore, a series of cyclic dynamic tests with various displacement amplitudes and frequencies have been conducted on the prototype of the RBD device based on the finite-element results. Finally, to analyze the dynamic behavior of the structure equipped with RBD, a finite-element model of a three-story reinforced concrete frame structure furnished with RBD dampers has been developed. The response of the structure has been evaluated under seismic loads, and a parametric study has been conducted to investigate the response of the structures with various rubber properties. The numerical analysis results indicated that the implementation of the RBD device leads to a reduction in the occurrence of plastic hinges and lateral displacements of the structure by up to 69%. This demonstrates the efficiency of the RBD device in diminishing the seismic load effect on the structure’s response.

Highly efficient diluent-free solvent extraction of uranium using mixtures of protonated trioctylamine and quaternary ammonium salts. Comparative Life Cycle Assessment with the conventional extractant

A more environmentally friendly solvent extraction process was formulated for uranium extraction using diluent-free extractants based on trialkylammonium compounds. The effect of ammonium cations and anions toward extraction efficiency, viscosity and phase separation was also evaluated. These systems were shown to be highly efficient and simple to implement as they rely on the same chemical components as those applied in the actual industrial process. It has also been demonstrated that using such alternatives allows not only to prevent third phase formation and subsequent extractant degradation, but also reduces the evaporation loss of solvent by a factor of 20. Among the systems investigated, the pure [TOAH]2[SO4] was selected as the simplest and most efficient. A comparative Life Cycle Assessment (LCA) was also conducted between this system and the conventional solvent to compare more objectively their sustainability. Results based on four environmental indicators show that the new system is 18 times less impactful. Contrary to expectations, this study also showed that the pure (diluent-free) extractant system needs to be at least 2 times more efficient in terms of metal extraction to become significantly more sustainable. Other main effects contributing to the LCA are derived from: (i) the production of chemicals, which is much more harmful for extractants than for aliphatic diluents, (ii) the loss of Volatile Organic Compounds (VOC) to the environment, and (iii) to a lesser extent, the additional centrifugation step that may be required to separate more viscous systems.

Multi-disciplinary performance comparison for selecting the optimal sustainable design of buildings structures with fluid-viscous dampers

Earthquake engineering aims to control the building performance and viscous damping systems are recognized for enhancing the seismic performance; however, performance is often assessed economically over other critical metrics. This study evaluates the seismic building performance with fluid viscous dampers from a sustainability perspective: economy, social factors, and environmental impact. It also identifies the optimal sustainable design considering the damping parameters α and C of the energy dissipation devices. Thus, a set of 28-story buildings equipped with viscous dampers is designed, where the damping properties (i.e., α and C) are varied to produce different structural alternatives. The FEMA P-58 methodology is utilized for evaluating the performance of the case studies. Then, the optimal design is defined as the building associated with the damping properties that minimize the expected annual loss considering repair costs, injuries, and carbon emissions. Results demonstrate that proper damping parameters selection significantly reduces expected annual losses compared to structures without supplemental damping system.

Experimental study on gas-liquid flow regimes of coaxial mixers equipped with a Rushton/pitched blade turbine and anchor

In view of the close relationship between gas-liquid mass transfer performance and flow regime, the coaxial mixer was selected as the research object, and the effects of rotation mode, inner impeller diameter, gas flow rate, and viscosity on flow regimes were experimentally investigated. The results showed that the main growth interval of the mass transfer coefficient was the loading regime, and the critical complete dispersion regime was an efficient and economic operation condition. In this state, the co-rotation mode had a low-power advantage compared to the counter-rotation mode. The anchor speed and gas flow rate could improve mass transfer performance, but at the expense of higher power consumption. Although it was easier to achieve the complete dispersion regime with a larger diameter impeller, the mass transfer performance was reduced at this time. The viscosity had a significant negative influence on gas-liquid dispersion and mass transfer performance. In terms of impeller combinations, PBTD+Anchor and RT+Anchor performed well in low and high viscous systems, respectively. In addition, applying the artificial neural network model to estimate the Ncd for the coaxial mixer correlated with the studied parameters to recognize the complete dispersion regime.

РЕГУЛИРОВАНИЕ ВЯЗКОСТИ ТЯЖЕЛОЙ НЕФТИ ПОЛИФУНКЦИОНАЛЬНЫМИ ДОБАВКАМИ НА ОСНОВЕ ПОВЕРХНОСТНО-АКТИВНЫХ ВЕЩЕСТВ

The aim of the work was to determine the influence of concentration and composition of polyfunctional additives consisting of surfactants and organic solvents (isopropyl alcohol and nephras C2) on the viscosity of high-resin heavy oil of the Ashalchinskoye field, which is a highly viscous colloidal disperse system. Viscosity measurements of the samples were carried out on Physica MCR 101 (Anton Paar) using a plate-to-plate instrument in the range of shear rate variation from 1 to 300 s-1. Dependences of effective viscosity on shear rate for the majority of the investigated systems indicate Newtonian flow behaviour, which is also confirmed by flow curves for all investigated heavy oil samples, i.e. the used additives are effective regulators of viscoelastic properties of the investigated oil. The viscosity of heavy oil decreases with increasing concentration of the studied additives, and the most effective additive (with concentration of 3 wt. %) based on surfactants with amino- and phosphate groups and easy-boiling solvent (de-aromatised catalytic reforming petrol) decreased oil viscosity by almost 47 %. As a result of comparing the effect of the studied polyfunctional additives and industrial additives, which are a mixture of polar and non-polar hydrocarbons, on the viscosity of heavy oil, it was found that, as a rule, their efficiency index is higher, and, consequently, their ability to improve the rheological properties of oil is higher, which indicates the potential possibility of their use to facilitate the transportation and processing of highly viscous oil. This article may be of interest to those studying the rheological properties of highly viscous heavy oil systems.

On the regularity of temperature fronts for the 3D viscous Boussinesq system

On the regularity of temperature fronts for the 3D viscous Boussinesq system

Stability of a one-dimensional full viscous quantum hydrodynamic system

Stability of a one-dimensional full viscous quantum hydrodynamic system

Behavior of Pasting Properties of Ohmic‐Heated Corn Starch Versus Moisture and Temperature Applied

AbstractStarch is an essential biopolymer for creating viscous food systems in the food industry. Viscosity behavior is unclear in the literature and varies with the thermal process and moisture content used. This study analyzed how ohmic heating affects the pasting properties of corn starch in response to changes in moisture and temperature. Corn starch is mixed with water at varying ratios (1:1, 1:3, and 1:5). The mixture is heated at 5 °C min−1 using an ohmic heating cooker to 80, 100, and 120 °C. Moisture affects pasting and starch properties. Peak viscosity varies with moisture content, decreasing from 5904 cP (native) to 3204–4510 cP at a 1:1 ratio. At a moisture ratio of 1:3, peak viscosity matched the native sample. Higher peak viscosity (6539 to 8772 cP) occurred at high moisture levels (1:3). Thermal properties confirmed different gelatinization degrees, which is evidenced by a shift in the x‐ray diffraction pattern from A‐type (native starch) to V‐type crystalline. The viscosity and physicochemical properties of corn starch depend on temperature and moisture levels. Moisture has a more significant impact on these properties than temperature. Therefore, varying the moisture content it can improve corn starch properties precisely, making it useful for the food industry.

Optimal decay rate and convergence of the incompressible viscous resistive MHD system

In this work, we investigate the optimal Lp(p≥2) time decay rate of global solutions to the incompressible viscous resistive MHD system with degeneration, and study its convergence to the incompressible viscous ideal MHD system as the resistivity ε goes to zero. The analysis is based on the high-low frequency decomposition and the uniform energy estimate of the system with respect to ε.

Identification of modal parameters and relaxation parameter for exponential non-viscous damping system using stochastic subspace method

Non-viscous damping parameters can be identified approximately based on the frequency response function of structures. However, it is difficult or expensive to perform vibration test and layout enough amount measured points for structures. The stochastic subspace method can identify modal damping parameters only using responses data from partial measured points. This paper extends the stochastic subspace method from the viscous damping system to non-viscous damping system. In addition, the eigenvalues of the second-order form equation of motion are proved equally to the state space formulation. The identified procedure of the proposed method is given in detail. Finally, the method is validated using three numerical examples for assessing its accuracy.

On the weak solutions for the MHD systems with controllable total energy and cross helicity

In this paper, we prove the non-uniqueness of three-dimensional magneto-hydrodynamic (MHD) system in C([0,T];L2(T3)) for any initial data in Hβ¯(T3) (β¯>0), by exhibiting that the total energy and the cross helicity can be controlled in a given positive time interval. Our results extend the non-uniqueness results of the ideal MHD system to the viscous and resistive MHD system. Different from the ideal MHD system, the dissipative effect in the viscous and resistive MHD system prevents the nonlinear term from balancing the stress error (R˚q,M˚q) as doing in [4]. We introduce the box flows and construct the perturbation consisting in seven different kinds of flows in convex integral scheme, which ensures that the iteration works and yields the non-uniqueness.

Seismic reduction principle and response analysis of variable damping viscous damper system

PurposeA new type of variable damping viscous damper is developed to meet the settings of different damping parameter values at different working stages. Its main principle and design structure are introduced, and the two-stage and multi-stage controllable damping methods are proposed.Design/methodology/approachThe theoretical calculation formulas of the damping force of power-law fluid variable damping viscous damper at elongated holes are derived, aiming to provide a theoretical basis for the development and application of variable damping viscous dampers. For the newly developed variable damping viscous damper, the dynamic equations for the seismic reduction system with variable damping viscous dampers under a multi-degree-of-freedom system are established. A feasible calculation and analysis method is proposed to derive the solution process of time history analysis. At the same time, a program is also developed using Matlab. The dynamic full-scale test of a two-stage variable damping viscous damper was conducted, demonstrating that the hysteresis curve is complete and the working condition is stable.FindingsThrough the calculation and analysis of examples, the results show that the seismic reduction effect of high and flexible buildings using the seismic reduction system with variable damping viscous dampers is significant. The program developed is used to analyze the seismic response of a broadcasting tower using a variable damping TMD system under large earthquakes. The results indicate that the installation of variable damping viscous dampers can effectively control the maximum inter-story displacement response of TMD water tanks and can effectively consume seismic energy.Originality/valueThis method can provide a guarantee for the safe and effective operation of TMD in wind and vibration control.

Energy harvesting from water streaming at charged surface.

Water flowing at a charged surface may produce electricity, known as streaming current/potentials, which may be traced back to the 19th century. However, due to the low gained power and efficiencies, the energy conversion from streaming current was far from usable. The emergence of micro/nanofluidic technology and nanomaterials significantly increases the power (density) and energy conversion efficiency. In this review, we conclude the fundamentals and recent progress in electrical double layers at the charged surface. We estimate the generated power by hydrodynamic energy dissipation in multi-scaling flows considering the viscous systems with slipping boundary and inertia systems. Then, we review the coupling of volume flow and current flow by the Onsager relation, as well as the figure of merits and efficiency. We summarize the state-of-the-art of electrokinetic energy conversions, including critical performance metrics such as efficiencies, power densities, and generated voltages in various systems. We discuss the advantages and possible constraints by the figure of merits, including single-phase flow and flying droplets.

Global exact controllability of the viscous and resistive MHD system in a rectangle thanks to the lateral sides and to distributed phantom forces

We consider the 2-D incompressible viscous and resistive magnetohydrodynamics (MHD) system in a rectangle, with controls on the lateral sides. The velocity satisfies Dirichlet boundary conditions, while the magnetic field follows perfectly conducting wall boundary conditions on the remaining, uncontrolled part of the boundary. We extend the small-time global exact null controllability result of Coron et al. in [Ann PDE 5(2):1-49, 2019] from Navier-Stokes equations to MHD equations, with a little help of distributed phantom forces, which can be chosen arbitrarily small in any given Sobolev spaces. Our analysis relies on Coron’s return method, the well-prepared dissipation method, long-time nonlinear Cauchy-Kovalevskaya estimates and Badra’s local exact controllability result.

Chemical profiling of botanical extracts obtained in NADES systems using centrifugal partition chromatography combined with 13 C NMR dereplication-Hypericum perforatum as a case study.

Natural deep eutectic solvents (NADES) have emerged as interesting extractants to develop botanical ingredients. They are nontoxic and biodegradable, nonflammable, easy to prepare, and able to solubilize a wide range of molecules. However, NADES extracts remain difficult to analyze because the metabolites of interest stay highly diluted in the nonvolatile viscous NADES matrix. This study presents a robust analytical workflow for the chemical profiling of NADES extracts. It is applied to Hypericum perforatum aerial parts extracted with the neutral mixture fructose/glycerol/water (3/1/1, w/w/w), and compared to the chemical profiling of a classical dry methanol extract. Exploiting polarity differences between metabolites, the H. perforatum NADES extract was partitioned in a liquid-liquid solvent system to trap the hydrophilic NADES constituents in the lower phase. The upper phase, containing a diversity of secondary metabolites from H. perforatum, was fractionated by centrifugal partition chromatography. All fractions were chemically investigated using a 13 C NMR dereplication method which involves hierarchical clustering analysis of the whole NMR dataset, a natural metabolite database for metabolite identification, and 2D NMR analyses for validation. Liquid chromatography-mass spectrometry (LC-MS) analyses were also performed to complete the identification process. A range of 21 metabolites were unambiguously identified, including glycosylated flavonols, lactones, catechins, phenolic acids, lipids, and simple sugars, and 15 additional minor extract constituents were annotated by LC-MS based on exact mass measurements. The proposed identification process is rapid and nondestructive and provides good prospects to deeply characterize botanical extracts obtained in nonvolatile and viscous NADES systems.

A simplified analysis method for estimating the peak responses of recentering structures with viscous damping systems

AbstractRecentering structure with a viscous damping system is an emerging structural system with remarkable seismic resilience. This system can exhibit sufficient energy‐dissipating capacity during a major earthquake and eliminate the residual deformation through recentering mechanism afterward. However, the seismic response of the considered system is still confusing due to its complex dynamic behavior. Thus, it is hard to estimate the peak responses of the system during a major earthquake. This study proposes a simplified analysis method for estimating the peak responses of recentering structures with viscous damping systems based on an equivalent two‐stage substitute model. Considering the considerable strain energy of recentering structures during vibrations, this method proposes to employ effective stiffness based on the equal‐energy principle in an equivalent two‐stage substitute model. Based on this concept, corresponding equations are derived for capturing the peak transient responses of the considered system. Results of response history analysis validate that the proposed method can reasonably estimate maximum relative displacement, relative velocity, and absolute acceleration. Given its satisfactory accuracy, this method is promising while conducting seismic design of recentering structures with viscous damping systems.

Global small solutions to the 3D compressible viscous non-resistive MHD system

Whether or not smooth solutions to the 3D compressible magnetohydrodynamic (MHD) equations without magnetic diffusion are always global in time remains an extremely challenging open problem. No global well-posedness or stability result is currently available for this 3D MHD system in the whole space [Formula: see text] or the periodic box [Formula: see text] even when the initial data is small or near a steady-state solution. This paper presents a global existence and stability result for smooth solutions to this 3D MHD system near any background magnetic field satisfying a Diophantine condition.

Implicit coupling methods for nonlinear interactions between a large‐deformable hyperelastic solid and a viscous acoustic fluid of infinite extent

AbstractThis paper addresses the challenges in studying the interaction between high‐intensity sound waves and large‐deformable hyperelastic solids, which are characterized by nonlinearities of the hyperelastic material, the finite‐amplitude acoustic wave, and the large‐deformable fluid–solid interface. An implicit coupling method is proposed for predicting nonlinear structural‐acoustic responses of the large‐deformable hyperelastic solid submerged in a compressible viscous fluid of infinite extent. An arbitrary Lagrangian–Eulerian (ALE) formulation based on an unsplit complex‐frequency‐shifted perfectly matched layer method is developed for long‐time simulation of the nonlinear acoustic wave propagation without exhibiting long‐time instabilities. The solid and acoustic fluid domains are discretized using the finite element method, and two different options of staggered implicit coupling procedures for nonlinear structural‐acoustic interactions are developed. Theoretical formulations for stability analysis of the implicit methods are provided. The accuracy, robustness, and convergence properties of the proposed methods are evaluated by a benchmark problem, that is, a hyperelastic rod interacting with finite‐amplitude acoustic waves. The numerical results substantiate that the present methods are able to provide long‐time steady‐state solutions for a nonlinear coupled hyperelastic solid and viscous acoustic fluid system without numerical constraints of small time step sizes and long‐time instabilities. The methods are applied to investigate nonlinear dynamic behaviors of coupled hyperelastic elliptical ring and acoustic fluid systems. Physical insights into 2:1 and 4:2:1 internal resonances of the hyperelastic elliptical ring and period‐doubling bifurcations of the structural and acoustic responses of the system are provided.

An improved gravimetric method with anti-solvent addition to measure the solubility of d-allulose in water

Anti-solvent assisted gravimetric (AAG) method as a novel approach was proposed to accelerate solubility measurement. The new method was to add the anti-solvent into the saturated solution to drive a fast crystallization, and then to evaporate the filtered solution in order to collect the residual solid particles that were added with dried filter cake particles to constitute the total mass of solute in the initial saturated solution. The solubility of d-allulose, as a model compound, was measured by AAG method at temperature of 283.15–353.15 K. Moreover, the measurement by AAG method had a higher processing efficiency and more convenient operation than the traditional gravimetric method, which perform better in the solubility measurement of most viscous systems.