Search results for "AMPER"
showing 10 items of 193 documents
Innovative modeling of Tuned Liquid Column Damper motion
2015
Abstract In this paper a new model for the liquid motion within a Tuned Liquid Column Damper (TLCD) device is developed, based on the mathematical tool of fractional calculus. Although the increasing use of these devices for structural vibration control, it is shown that existing model does not always lead to accurate prediction of the liquid motion. A better model is then needed for accurate simulation of the behavior of TLCD systems. As regards, it has been demonstrated how correctly including the first linear liquid sloshing mode, through the equivalent mechanical analogy well established in literature, produces numerical results that highly match the corresponding experimental ones. Sin…
Stochastic seismic analysis of structures with nonlinear viscous dampers
2007
Fluid damper devices inserted in buildings or bridges are commonly used as energy sinks for seismic protection. In the response analysis of structures with filled damper devices the main problem exists in the strong nonlinear behavior of such equipment, as a consequence the differential equation of motion remains nonlinear and the response spectrum analysis still cannot be applied. In this note, by using the concept of power spectral density function coherent with the elastic response spectrum and by using the statistical linearization technique, expressions for finding the equivalent linear damping have been found. Comparisons with results obtained by Monte Carlo simulations confirm that f…
Low angle bending detection semi-transparent piezoresistive sensor
2022
We designed, fabricated, and validated a piezoresistive bending sensor, a fundamental component of wearable electronic devices for monitoring human motion. The most diffused opaque carbon-based resistance flex sensors suffer from low detection for small bending angles. The sensor we here present is based on a semi-transparent active material (fulleropyrrolidine bisadducts polymer) and has the remarkable advantage of good electrical properties for low bending angles. The fabrication steps are effective since a pre-patterned ITO/PET surface is functionalized by chronoamperometric deposition, and the silver electrical contacts are inkjet printed. We propose a fitting function of the measured t…
Quantification of electrochromic kinetics by analysis of RGB digital video images
2018
A new, rapid, and practical procedure to obtain quantitative kinetic information of electrochromic materials is proposed. When the transition between two colors on a colored electrode surface is monitorized by digital video, the analysis of pixel color intensity (I) in sequential RGB digital images allows us to precise the half-life time (t1/2) of the color change since a maximum value of the standard deviation of the pixel intensity (σ(I)) is reached. We simulated and analyzed the evolution of standard deviation during an electrochromic transition in different circumstances (kinetic and diffusion control). As an example of application, electrochromic transitions of a thin film model, the P…
Chronoamperometry of prussian blue films on ITO electrodes: Ohmic drop and film thickness effect
1999
Abstract The chronoamperograms associated with the reduction of prussian blue films deposited onto indium tin oxide (ITO) electrodes to the Everitt’s salt form, are influenced by the ohmic drop effect. These chronoamperometric curves have been simulated by means of a numerical finite difference model which is able to explain their shape and their dependence on the thickness of the film and on the uncompensated resistance. An analytical expression which describes the dependence of current against time at initial times considering the ohmic drop effect has also been proved when applied to these chronoamperometric curves at short times.
On a time-depending Monge-Ampère type equation
2012
Abstract In this paper, we prove a comparison result between a solution u ( x , t ) , x ∈ Ω ⊂ R 2 , t ∈ ( 0 , T ) , of a time depending equation involving the Monge–Ampere operator in the plane and the solution of a conveniently symmetrized parabolic equation. To this aim, we prove a derivation formula for the integral of a smooth function g ( x , t ) over sublevel sets of u , { x ∈ Ω : u ( x , t ) ϑ } , ϑ ∈ R , having the same perimeter in R 2 .
Alma Mater: 2014/ Vasara
2014
Andra Čudare. Studentu taisnības bruņinieks Kirils Solovjovs -- Katrīna Žukova. Zinību lauks – atmiņu laiks -- LU māju noslēpumi atklājās Muzeju naktī -- LU Preses centrs. Zinātne – tas ir forši un radoši -- Sarmīte Rutkovska. Futbols kā tikšanās vieta -- LU Zinātnes un tehnikas vēstures muzejs, LU Preses centrs. Fotostāsts. Studentu mode cauri laikiem -- Laine Dobulāne. Atjauno modernākās ērģeles Latvijā -- LU Preses centrs. Praktiķi dalās pieredzē ar topošajiem kolēģiem -- LU Preses centrs. Reportāža. Psihiskas performances un «Ātrā palīdzība» jauno grupu konkursā «Hadrons» -- LU Bibliotēka. Ciparojot šodienai un nākotnei: LU Bibliotēkas pieredze digitalizācijā -- Kārlis Dārznieks. Jau 85…
Comparison results for Monge - Ampère type equations with lower order terms
2003
In this paper we deal with Monge-Ampère type equations in two dimensions and, using the symmetrization with respect to the perimeter, we prove some comparison results for solutions of such equations involving the solutions of conveniently symmetrized problems.
Experimental determination of viscous damper parameters in low velocity ranges
2017
In the last decades many strategies for seismic vulnerability mitigation of structures have been developed through analytical studies and experimental tests. Among these, energy dissipation by external devices assumes a great relevance for the relative design simplicity, even if applied to complex structures, and the effectiveness in reducing seismic demand. In particular, the use of fluid viscous dampers represents a very attractive solution because of their velocity-dependent behaviour and relatively low costs. The application on structures requires specific study under seismic excitation and a particular care of structural details. In this context the use of proper constitutive models fo…
On the moving load problem in beam structures equipped with tuned mass dampers
2017
This paper proposes an original and efficient approach to the moving load problem on Euler–Bernoulli beams, with Kelvin–Voigt viscoelastic translational supports and rotational joints, and in addition, equipped with Kelvin–Voigt viscoelastic tuned mass dampers (TMDs). While supports are taken as representative of external devices such as grounded dampers or in-span supports with flexibility and damping, the rotational joints may model rotational dampers or connections with flexibility and damping arising from imperfections or damage. The theory of generalised functions is used to treat the discontinuities of the response variables, which involves deriving exact complex eigenvalues and eigen…