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The emergence of elevated concentrations of bromate, classified as a 2B type carcinogen, in drinking water following the treatment of water supplies with ozonation and other oxidation methods has underscored the importance of developing methods for reliable and rapid screening of drinking water. In this work, we report the use of electro activated riboflavin (RF) impregnated Ketjen black (KB) modified screen-printed electrode (el RF@KB-SPE) for the determination of bromate. The sensing surfaces were subjected to morphological and structural characterization using scanning electron microscopy and Raman spectroscopy. These analyses confirmed the successful modification of the electrode with an extended el RF@KB porous coating. Based on cyclic voltammetry (CV) and electrochemical impedance spectroscopy measurements, the response of el RF@KB-SPE towards bromate can be described through a dual mechanism involving i) an autocatalytic chemical/electrochemical process that predominantly occurs in the finite length pores of KB, and ii) an RF-mediated electrocatalytic process. Notably, the data demonstrated that the advanced electrocatalytic properties of the otherwise electrocatalytically inactive absorbed RF molecules are endowed after a simple electro activation process (three CV scans). Amperometric measurements at −0.05 V vs. Ag/AgCl revealed a linear relationship between the current response and the concentration of bromates over the concentration range 0.50−18.0 μM, achieving a limit of detection (3 σ /slope) of 0.04 μM. The interference effect of various electroactive species was investigated demonstrating that el RF@KB-SPE is highly selective to bromate. The analytical utility of the method was evaluated in spiked tap water samples. Recoveries were 91.2 − 106.4 %. [Display omitted] • Bromate sensing in electroactivated riboflavin impregnated carbon black (KB) SPE. • CV and EIS data support a dual autocatalytic redox mediation mechanism. • Electrocatalysis occurs in a finite-length diffusion regime within the pores of KB. • Impregnation of riboflavin in KB porous promotes the electroanalysis of bromate. • Data demonstrated high selectivity and analytical utility in water samples. [ABSTRACT FROM AUTHOR]

In this paper, a new algorithm to solve the elastic quarter-space, the eighth-space and the finite-length-space contact problems is proposed. This corresponds to an extension of the Hertz theory. The theoretical foundations of such a problem are limited, due to the presence of displacements at the free edges- or stresses at the virtual edges — resulting to complex boundary conditions. The new approach presented here is 3D and based on Guilbault's ingenious fast correction method. In this approach, the edge effects are taken into account by introducing two corrective factors ψ 1 , ψ 2 respectively on the (O x) and (O z) axes to replace the mirror pressure iterative process of Hetenyi. The exact numerical values of these two correction factors are derived analytically. The results show that the free edge can substantially increase locally the contact pressure and therefore the stresses and displacement fields if close to the contact area. So the pressure field and the contact zone present an asymmetry which is more pronounced as the free edge is getting closer. This study is carried out on spaces with one, two and four free edges which will be respectively called: quarter-space, eighth-space and finite-length-space. A validation is performed using a Finite Element Method (FEM) analysis. A parametric study is also performed to exhibit the differences with the Hertz solution, including in the situation where one expects the truncation of the contact area when the free edge is virtually located within the Hertz contact area. • A new algorithm to solve the elastic finite space contact problem is proposed. • Two corrective factors called ψ 1 and ψ 2 are derived from hyper-geometric series. • Surprisingly the contact print moves away from the free edge when it comes closer. • The maximum contact pressure increases when the free edge comes closer. • The model has been validated with the Finite Element Method. [ABSTRACT FROM AUTHOR]

This paper investigates the sound transmission of a thick-walled cylindrical shell of finite length excited by an exterior turbulent boundary layer (TBL). The boundary conditions at both ends of the structure are considered to be simply supported. To drive wave propagation into the thick-walled cylindrical shell, the Extended Full Method (EFM) is applied. Additionally, Corcos and Efimtsov models are employed to characterize pressure fluctuation caused by the TBL. Since the equations of acoustic pressures and shell displacements are extended in a double Fourier series, the convergence of the solutions in both axial and circumferential modes is investigated. The validation of the results of the present method is being done using the Statistical Energy Analysis (SEA) method, with the structure being modeled in VA One software. The results indicate an acceptable agreement between the SEA method and EFM. Analytical predictions reveal that sound transmission by finite-length thick-walled cylindrical shells, with a ratio of radius to thickness less than 18.5, is significantly reduced with increasing shell thickness in the low-frequency range. However, in the frequency range above 5000 Hz, this trend in transmission continues to decrease. Also, it is shown by the results that as turbulent pressure and free flow speed increase, sound transmission within the structure is enhanced. • the Extended Full Method (EFM) is presented to solve the equations. • Investigating the effect of turbulent flow on a thick-walled cylindrical shell. • The validation of the result using the Statistical Energy Analysis (SEA) method. • Increasing density decreases sound radiation, particularly in the high-frequency range. • Increasing the thickness of the shell resulted in a reduction in sound transmission through the structure. [ABSTRACT FROM AUTHOR]

• Series solutions of the pressure distribution for the finite-length TPJB considering the pad deformation. • Analytical analysis of design parameters for the finite-length tilting pad journal bearing. • The thermal effect and pad deformation of bearings cannot be ignored at a high rotation speed. • The length-diameter ratio and preload factor have obvious but different effects on the bearing performance. This paper applies the variable separation method to the hydrodynamic pressure calculation of finite-length tilting pad journal bearings under Reynolds boundary conditions, and a series solution of the Reynolds equation is obtained based on the Sturm-Liouville theory, which considers pad deformation. The thermal effect is also taken into account. A comparison of the present solutions is made with the results obtained by other applied methods, as well as past and recent published data, and good agreement is noted. The steady-state and dynamic performance of a four-pad tilting pad journal bearing are investigated by the load capacity, pressure distribution, friction force, lubricant effective viscosity, journal center velocity, journal center orbits, and phase portrait under the proposed series solution of the Reynolds equation. This study contributes to quickly evaluating the nonlinear dynamic performance of a tilting pad journal bearing rotor system and supporting the nonlinear dynamic design of the system. [ABSTRACT FROM AUTHOR]

Large Eddy Simulation (LES) is used to numerically simulate the flow around a finite-length inclination circular cylinder. The Reynolds number is fixed at 3900, and the inclination angle θ is varied from 0° to 60° in increments of 7.5°. The study analyzes the cylindrical force, vortex shedding frequency, wake structure, instantaneous flow field, and time-averaged flow field at different inclination angles. The numerical simulation of flow over a vertical circular cylinder was verified, and the results were found to be in good agreement with the published results. Then the study of flow pass inclination circular cylinder was carried out using the validated model, and the results show that the inclination angle has great on the forces and vortex shedding mode. The independence principle only can be applied at small inclination angles. • Large Eddy Simulation (LES) is used to numerically simulate the flow around a finite-length inclination circular cylinder. • The study analyzes the cylindrical force, vortex shedding frequency, wake structure. • Instantaneous flow field, and time-averaged flow field at different inclination angles. • The independence principle only can be applied at small inclination angles. [ABSTRACT FROM AUTHOR]

In this study, a Maxwell–Rayleigh-type model is investigated, describing a unidimensional lattice with a finite length, where the unit cell includes hosting and resonant masses mutually connected by elastic springs. The configuration selected is inspired by the specific engineering design to be discussed: however, the theoretical approach pursued is rather general and can be easily generalized to different scenarios. By the heuristic homogenization based on a Piola's Ansatz, an equivalent continuum is specified: through a variational approach, resting on the minimization of the Hamilton's action functional, a dispersion relation is deduced, revealing the existence of a band gap. Such a continuous interval of frequencies, inside which the propagation of waves is inhibited, can be tuned controlling the features of the original system. Thereafter, exploiting the same equations, the stationary elasto-dynamic response for a chain with a finite length is also deduced, corresponding to standing waves. On the basis of such results, the preliminary design of a linear chain with a finite number of cells is carried out. By the present strategy proper boundary conditions are deduced to be prescribed at the ends of the 1D lattice sample, and not over the unit cell (as it occurs in Bloch–Floquet approach with periodicity conditions). To realize the mutual elastic connections between unequal masses fitting the problem constraints, tensegrity prisms are selected, including compressed bars and tensioned cables, for which it is possible to govern the tangent axial stiffness through the cable pre-tensioning. We analyze the scenario in which the band gap coincides with the interval 1 − 10 Hz , indicating an appropriate geometry and suitable engineering materials for the tensegrity elements. • Heuristic homogenization of a Maxwell–Rayleigh finite length lattice. • Boundary conditions through Hamilton's action minimization. • A frequency band gap tunable by the unit cell parameters. • Design of a linear chain with a finite number of masses and tensegrity prisms. • Selection of suitable materials for band gap in the frequency range 1–10 Hz. [ABSTRACT FROM AUTHOR]

The paper investigates a problem of forced vibrations of two finite length metabeams: one is with periodically arranged internal hinges and the second one with periodically arranged internal hinges and external supports. Based on the Euler–Bernoulli beam theory and the transfer matrix method, general solutions of the periodic beams are obtained. Applying the Bloch-Floquet theory, the explicit expressions are derived defining the metabeams band gap structures. The corresponding band gap dispersion curves are plotted and analysed. It is shown that when the frequency of forced vibrations coincides with the band gap frequencies a strong localization of flexible waves occurs at the interfaces of the periodic beams. The localization of flexible waves increases significantly with the number of hinges and supports. • Internal hinges and external supports in beams open wide frequency band gaps. • Strong localization of flexural waves occurs within frequencies of band gaps. • The localization is stronger for larger numbers of hinges and external supports. • The resonance frequencies are mostly outside the forbidden frequency band gaps. [ABSTRACT FROM AUTHOR]

The spanwise characteristics of flow passing a yawed finite circular cylinder are numerical investigated at the yaw angle of 30°, aspect ratio of 9 and Reynolds number of 3900 using Large Eddy Simulation. The wake vortical structure and streamlines manifest that the regular Karman vortex street breaks down and there exists axial flow along the cylinder axis. To get further insight into the spanwise characteristics, the cylinder is virtually divided into nine equal-spaced sections along the cylinder span, and the drag and lift force coefficients of each section are monitored. By comparing the drag coefficients of these nine cylinder sections, it is found that the anti-clockwise torque is imposed on the cylinder. Furthermore, the FFT analyses of these nine fluctuating lift coefficients are carried out to reveal the characteristics in the frequency domain. It is shown that the nine spectra demonstrate different behaviours, by which the wake vortical structure is identified spanwise as three regions, two end-plate regions and the midspan region. In the downstream end-plate region, the vortex-shedding is well organized, whereas in the upstream end-plate region the wake vortex structure manifests itself stronger three-dimensional and severely irregular. And in the midspan region, the peak of frequency spectra is broadband and the regular Karman vortex street is not yet noticeable to identify. [ABSTRACT FROM AUTHOR]

Abstract The paper presents linearized coefficients for finite-length journal bearings based on the HD forces with multiplicative correction polynomials applied to the infinitely short and the infinitely long solutions under the assumption of π -film boundary condition. Based on the linear theory, stability thresholds and their dependence on the length-to-diameter ratio are investigated. Moreover, using the numerical continuation method the change of the generalized Hopf bifurcation which separates regions with subcritical and supercritical Hopf is documented. All results are compared with those of the solution obtained using the finite differences method. Highlights • Stiffness and damping coefficients for the finite-length journal bearings. • Analysis of the influence of length-to-diameter ratio on the dynamic coefficients. • Stability analysis of a single finite-length bearing using Routh-Hurwitz criterion. • Determination of stability curve properties using numerical continuation. • Comparison with FDM-based solution. [ABSTRACT FROM AUTHOR]