Cancellation Phenomena Research Articles

Experimental study of hue cancellation and its mechanism exploration

To research the distinctions between dichoptic color vision and naked-eye color vision in the human vision system, this study carried out psychophysical experiments to explore hue cancellation phenomena in both dichoptic and naked-eye visual conditions. The experimental results show that dichoptic hue cancellation (DHC) not only occurs in the red and green (R-G), yellow and blue (Y-B), and yellow-green and purple (YG-P) color directions in CIELAB space but also requires color desaturation. In naked-eye vision, a specific color for each color is capable of inducing hue cancellation. The experimental results imply that hue cancellation in naked-eye vision may be a complementary phenomenon. The process of viewing two hues to produce a third hue should be completed in the retina.

Hate speech and cancellation phenomena and the impacts on young people's communication in digital environments.

The ICT Domicílios 2021 survey reveals the growth in the use of the internet in Brazil compared to periods prior to the Covid 19 pandemic. However, this expansion is not reflected in the percentages of selfauthored content posted by users: only 31% reported that they share something of their own creation, be it a text, image, photo, video or music. Among young people from Salvador (Bahia, Brazil) who are interested in politics, Silva's research (2022) revealed that only 34% claim to publish authorial content. Among the reasons given by young people, they mention fear of cancellation and hate speech. This article analyzes data from this survey in the light of discussions on infocommunicative literacy. We conclude that public policies in the country need to advance in terms of guaranteeing the right to the internet associated with education for the ethical, critical and democratic use of information and communication.

Nonlinear Dynamic Analysis of a Curved Sandwich Beam with a Time-Dependent Viscoelastic Core Using the Generalized Differential Quadrature Method (GDQM)

This paper focuses on the geometrically nonlinear dynamic analyses of a three-layered curved sandwich beam with isotropic face layers and a time-dependent viscoelastic core. The boundary conditions and equations of motion governing the forced vibration are derived by using Hamilton’s principle. The first-order shear deformation theory is used to obtain kinematic relations. The spatial discretization of the equations is achieved using the generalized differential quadrature method (GDQM), and the Newmark-Beta algorithm is used to solve the time variation of the equations. The Newton–Raphson method is used to transform nonlinear equations into linear equations. The validation of the proposed model and the GDQM solution’s reliability are provided via comparison with the results that already exist in the literature and finite element method (FEM) analyses using ANSYS. Then, a series of parametric studies are carried out for a curved sandwich beam with aluminum face layers and a time-dependent viscoelastic core. The resonance and cancellation phenomena for the nonlinear moving-load problem of curved sandwich beams with a time-dependent viscoelastic core are performed using the GDQM for the first time, to the best of the authors’ knowledge.

Historical Review on Resonance and Cancellation of Simply Supported Beams Subjected to Moving Train Loads: From Theory to Practice

The advent of railways and especially highspeed railways marks great strides in human transportation history. To guarantee exclusive right-of-way, highspeed railways are often built on equal simply supported beams resting on piers. In this paper, a historical review will be given of the resonance and cancellation phenomena observed for simply supported beams traveled by a set of moving loads, as they are typical of highspeed railways. The phenomenon of resonance was observed by early investigators including Timoshenko, Bolotin, Frýba, Matsuura, etc. However, the phenomenon of cancellation was noted lately in 1997 by Yang et al. By letting the conditions of resonance and cancellation coincident, they proposed the optimal span length for suppressing the resonance of simple beams, which is equal to 1.5 times the car length. This 1.5 times rule has been verified and adopted in the design of some highspeed railways. In this article, the theoretical solution for the problem will be revisited for unveiling the key parameters such as the resonance speed (in temporal domain) and resonance wavelength (in spatial domain). Then a rather in-depth review will be given of existing works on the resonance and cancellation of railway bridges from the waves perspective. Some new developments along these lines will also be identified.

Internal and External Cancellation Conditions for Free Vibration of Damped Simple Beams Traversed by Successive Moving Loads

In this paper, the internal and external cancellation phenomena for damped beams subjected to multi-moving loads are investigated in detail. To start, the theory for the vibration of a simply supported beam is revisited by including the effect of damping. For the first time, a simple expression is derived for the free vibration of the damped beam under multi-moving loads. Based on the concept of local minimum, two cancellation conditions are identified. One is the internal cancellation, which relates to the inherent property of the beam and is conventionally known. The other is the newly formulated external cancellation that relates to the number and spacing of moving loads. For comparison, both the resonant condition and the optimal criterion for span length of the bridge are also briefed. By comparing with the classical solution, the present simple expression for the free vibration of the beam is firstly validated. Then the factors affecting the cancellation are investigated against various load cases and damping levels. The results show that external cancellation occurs more frequently due to the increase in the number and spacing of the moving loads. The damping of the beam has a leaking effect on cancellation, in that nonzero vibration may occur, but it is also quickly damped out by damping itself.

Resonance and cancellation phenomena in partially clamped simply supported beam bridges under moving trains

Since the development of new railway lines of high speed, the dynamic response of bridges belonging to them constitutes a subject interest for researchers and engineers, in particular at resonance. In the present work, an analytical approach is developed to analyze the dynamic response of a single ballasted track railway bridges supported by identical rotational springs and subjected to the circulation of moving loads at constant speeds. Although the introduction of rotary springs at the ends of the deck enhances the choice of the appropriate analysis model, where most of the contributions reported in this field do not consider this effect. The central idea of the proposed model is based on analyzing the continuity effect of the ballasted track (rails and ballast) on the dynamic response of railway bridges, with taking into account an axial force that models the effect of prestressing, longitudinal ballast-bridge interface, axial displacement, force braking. The equation of motion of the system is derived by using the Hamilton’s principle, two dynamic case studies of a simply supported and simply supported partially clamped Euler-Bernoulli beam are presented. The results revealed that the compression force presents an additional stiffness which affects the critical velocity and that the continuity of the track modeled by rotational springs at the beam’s end, as it increases the dynamic response decreases. Also, a dynamic analysis for the conditions for maximum response and cancellation in free vibration are derived and interpreted particularly the effect of the geometric scheme of train axles. Equating the condition for resonance of maximum free response and cancellation, cancelled resonance are obtained.

Energy harvesting analysis in railway bridges: An approach based on modal decomposition

In this paper the authors investigate the energy harvesting in railway bridges and analyse the performance under different operational conditions. An approximation based on modal superposition is proposed for the computation of the energy harvested from train-induced bridge vibration. This approach is consistent with the analytical modal solutions of the simply-supported Bernouilli-Euler beam transverse response under moving loads. The influence of the bridge maximum dynamic response and cancellation phenomena, the tuning effect of the harvester device and the relevance of different modal contributions on the harvested energy are studied using a single-degree of freedom system as a simplistic mechanical approach. Later, a piezoelectrically coupled lumped parameter model is used to investigate the available energy due to High-Speed train passages at different circulating speeds. Finally, the feasibility of energy harvesting is evaluated from the experimental data measured by the authors in a railway bridge from the Madrid-Sevilla High-Speed line. The obtained results allow quantifying the harvested energy in a time window of three and a half hours and twenty train passages.

Fluctuations of nodal sets on the 3-torus and general cancellation phenomena

Fluctuations of nodal sets on the 3-torus and general cancellation phenomena

Resonance and cancellation phenomena in two-span continuous beams and its application to railway bridges

The objective of this study is to evaluate the vibratory response of two-span continuous beams subjected to moving loads and, in particular, to investigate the maximum resonance and cancellation of resonance phenomena. The main practical interest is the evaluation of the maximum acceleration response in railway bridges, which is one of the most demanding Serviceability Limit States for traffic safety according to current regulations. Two-span continuous bridges, in their simplest version (i.e. uniform identical spans), present antisymmetric and symmetric modes with closely spaced natural frequencies, leading to a more involved dynamic behaviour than that of simply-supported bridges. First, the free vibration response of a Bernoulli-Euler two-span beam after the passage of a single load at constant speed is formulated analytically, and non-dimensional speeds leading to cancellation or maximum response in free vibration are obtained for each mode. Then, these conditions are equated to resonant speeds induced by equidistant load series, and span length-to-characteristic distance ratios causing cancelled out resonances, or remarkably prominent ones, are obtained. Based on the previous derivations, a methodology for detecting which could be the most aggressive trains for a particular structure based on pure geometrical considerations is discussed. Finally, the applicability of the theoretical derivations is shown through the numerical analysis of two real bridges belonging to the Swedish railway network.

On the vibrations of axially graded Rayleigh beams under a moving load

In the present investigation, the forced and free vibrations of axially functionally graded (AFG) Rayleigh and Euler-Bernoulli (EB) beams subjected to a moving load are studied and compared, aiming at performance enhancement of transportation systems. Also, for the first time, a precise mathematical modeling is obtained to analyze the influence of various key factors such as axial material gradation and rotary inertia factor on the critical speed, dynamic magnification factor, mechanisms of cancellation, and maximum free vibration of the system. Model verification is performed with the available results in the literature, and a good agreement is observed. Furthermore, the dynamical responses of the system acquired from the analytical and numerical approaches are in good agreement. It is demonstrated that for the gradient parameter, which is lower and higher than the critical value, the material properties variation has a reverse effect on the forced-free vibration amplitudes. Besides, it is concluded that, compared with the conventional isotropic EB beams, by selecting appropriate values of rotary inertia factor and gradient parameter in the AFG Rayleigh beams, the cancellation and maximum free vibration phenomena can be controlled. The results of this study can serve as a comprehensive benchmark to optimally design inhomogeneous structures under moving loads.

Mitigation Methods for Passive Intermodulation Distortion in Circuit Systems Using Signal Compensation

An equivalent circuit model of a passive system with nonlinear characteristics was developed to simulate the forward and reversed passive intermodulation product (PIMP) powers. Mitigation methods based on signal compensation were proposed and used to reduce the interferences of passive intermodulation (PIM). The cancellation phenomena of third-order PIMP powers were observed both in the active and passive signal compensation simulations, followed by some theoretical analysis. The advantages and disadvantages of each mitigation method were discussed in detail, providing flexible selections in low-PIM design and PIM elimination in specific applications.

Maximum resonance and cancellation phenomena in orthotropic plates traversed by moving loads: Application to railway bridges

The vibrational response of railway bridges is an issue of main concern, especially since the advent of High-Speed traffic. In the case of short-to-medium lengths and simply-supported spans excessive transverse acceleration levels may be induced at the platform, with detrimental consequences for passengers and infrastructures. The orthotropic plate has proven to be an appropriate model for the prediction of the response of certain typologies in the aforementioned cases such as multiple girder decks, solid or voided slabs or filler-beam multiple-track decks. In this contribution, the vibrational response of orthotropic plates, simply and elastically supported, circulated by vertical moving loads is investigated. First, maximum free vibration and cancellation conditions are derived analytically. From these, bridge span length-characteristic distance ratios leading to maximum and minimum resonances under series of equidistant loads are depicted. Second, the applicability of these ratios in oblique decks is analysed for the most common first three mode shapes: first longitudinal bending, first torsion and first transverse bending modes, and the errors in relation to the straight reference case are bounded. To this end, an extensive bridge catalogue of girder bridges is designed in the range of lengths of interest, covering flexural stiffnesses typical from both conventional and High-Speed railway lines. Finally, the applicability of the previous theoretical results is exemplified with experimental measurements performed on a bridge from the Spanish railway network.

Phase singularities in complex arithmetic random waves

Complex arithmetic random waves are stationary Gaussian complex-valued solutions of the Helmholtz equation on the two-dimensional flat torus. We use Wiener-It\^o chaotic expansions in order to derive a complete characterization of the second order high-energy behaviour of the total number of phase singularities of these functions. Our main result is that, while such random quantities verify a universal law of large numbers, they also exhibit non-universal and non-central second order fluctuations that are dictated by the arithmetic nature of the underlying spectral measures. Such fluctuations are qualitatively consistent with the cancellation phenomena predicted by Berry (2002) in the case of complex random waves on compact planar domains. Our results extend to the complex setting recent pathbreaking findings by Rudnick and Wigman (2008), Krishnapur, Kurlberg and Wigman (2013) and Marinucci, Peccati, Rossi and Wigman (2016). The exact asymptotic characterization of the variance is based on a fine analysis of the Kac-Rice kernel around the origin, as well as on a novel use of combinatorial moment formulae for controlling long-range weak correlations.

Resonance and cancellation phenomena caused by equidistant moving loadings in a periodic structure — A pile-supported periodic viaduct

Abstract In this paper, the resonance and cancellation phenomena occurring in a periodic structure-- a pile-supported periodic viaduct subjected to multiple equidistant moving loadings (MEML) are investigated. For this purpose, the representation for the dynamic response of the periodic viaduct to a single moving loading (SML) is introduced first. In order to take account of the pile-soil-structure interaction when evaluating the response of the periodic viaduct to a SML, a wavenumber domain boundary element method (WDBEM) model for the pile-row-soil system is employed to determine the compliances of the piles. By superposing the responses of the viaduct to all SMLs constituting the MEML, the representation for the dynamic response of the periodic viaduct to the MEML is obtained. With the representation for the MEML response of the viaduct, the resonance and cancellation conditions for the viaduct are derived. For the high speed MEML, when the time interval between two neighboring moving loadings is equal to the integer or half-integer multiples of the period of one of the dominant resonance peaks of the corresponding SML response of the viaduct, resonance or cancellation occurs. The predicted resonance and cancellation phenomena are confirmed by the numerical results presented in this paper.

Vertical Electrical Sounding (VES. Investigation of Aquifer and Potential Clay Materials in Douala Subbasin (Cameroon, Central Africa)

<span style="font-size: 10.5pt; font-family: 'Times New Roman','serif'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA;" lang="EN-US">Vertical electrical sounding was done at 47 points using an ABEM 1000 Terrameter and a set of cables that could probe up to a depth of 500m. Resistivity was determined in two sites located in the district of Douala III (Bomkoul and Ngoma) 6 km west of the main town on the left bank of the Wouri River. The choice of these neighbourhood is as a result on the one hand, the presence of clay deposits from which sections have helped to configure resistivity data with those of geoelectric sections, and on the other hand, by the ability to extend the measuring device over great distances without being hindered by urbanization. The depths of investigation range from a minimum of 30 m and a maximum of 120 m. The results show a wide variability in resistivity values throughout the study area; it may be related to the high variability of facies described on sections by diggers. This variability may be due to the complexity of deposits recorded in the Douala sedimentary basin and also because of the presence of water in both sandy and clay sediments due to climate. The suggested resistivity is between 20 and 600ohm.m for clays and greater than 1000 ohm.m for sand. Given the weak thickness of some layers, the cancellation phenomena that affect very thin layers between two layers of different geoelectric properties of the latter have been observed, thus assigning to clay layers, sand resistivity.</span>

Codimension two souls and cancellation phenomena

For each m≥0 we find an open (4m+9)-dimensional simply connected manifold with complete nonnegatively curved metrics whose souls are nondiffeomorphic, homeomorphic, and have codimension 2. We give a diffeomorphism classification of the pairs (N,soul) when N is the total space of a nontrivial complex line bundle over S7×CP2; up to diffeomorphism there are precisely three such pairs, distinguished by their nondiffeomorphic souls.

Vibrations of railway bridges for high speed trains under moving loads varying in time

Experimental measurements show that the loads transmitted from train axles contain not only a constant component, but also significant alternating components in the range 0–6 Hz. Using the model of a simply supported beam transited by moving loads varying in time, the authors analyse the deflections produced in small and medium span bridges under the action of combined loads. A first case is the deflection under the combined load owing to a constant component together with an alternating component and transmitted by a single axle, while a second case is the study of the combined action of several composite loads transmitted by equidistantly spaced axles. The effects of the speed and of the frequency and phase of the alternating components are analysed in detail, determining the conditions under which, in the case of forces transmitted by several axles, resonance and cancellation phenomena may occur.

‘Screening’ of universal van der Waals–Casimir terms by Coulomb gases in a fully finitetwo-dimensional geometry

This paper is a continuation of a previous one (Jancovici and Šamaj, 2004 J. Stat.Mech. P08006) dealing with classical Casimir phenomena in semi-infinite wallgeometries. In that paper, using microscopic Coulomb systems, the long-rangedCasimir force due to thermal fluctuations in conducting walls was shown to bescreened by the presence of an electrolyte between the walls into some residualshort-ranged force. Here, we aim to extend the study of the screening (cancellation)phenomena to universal Casimir terms appearing in the large-size expansions of thegrand potentials for microscopic Coulomb systems confined in fully finite 2Dgeometries, in particular the disc geometry. Two cases are solved exactly: thehigh-temperature (Debye–Hückel) limit and the Thirring free-fermion point. Similarities andfundamental differences between fully finite and semi-finite geometries are pointed out.

DYNAMIC RESPONSE OF A HORIZONTALLY CURVED BEAM SUBJECTED TO VERTICAL AND HORIZONTAL MOVING LOADS

Analytic solutions are derived for a horizontal curved beam subjected to vertical and horizontal moving loads. The horizontal moving loads may be regarded as the centrifugal forces generated by vehicles moving along a curved path, which were rarely studied by previous researchers. Both a single moving load and a series of equidistant moving loads are considered. By superposition of the waves generated by consecutively moving loads on the curved beam, the conditions for the resonance and cancellation phenomena to occur are established. Compared with the numerical approaches, the present approach has the advantage that it provides clear physical insights into the various vehicle-induced phenomena on curved beams, while allowing us to identify the key parameters involved.

CPviolating phases, nonuniversal soft breaking, and D-brane models

The question of $\mathrm{CP}$ violating phases and electric dipole moments (EDMs) for the electron ${(d}_{e})$ and the neutron ${(d}_{n})$ for supergravity models with nonuniversal soft breaking is considered for models with a light $(\ensuremath{\lesssim}1\mathrm{TeV})$ mass spectrum and R-parity invariance. As with models with universal soft breaking (MSUGRA) one finds that a serious fine-tuning problem generally arises for ${\ensuremath{\theta}}_{0B}$ (the phase of the B soft breaking parameter at the GUT scale), if the experimental EDM constraints are obeyed and radiative breaking of ${\mathrm{SU}(2)}_{L}\ifmmode\times\else\texttimes\fi{}{U(1)}_{Y}$ occurs. A D-brane model where ${\mathrm{SU}(3)}_{C}\ifmmode\times\else\texttimes\fi{}{U(1)}_{Y}$ is associated with one set of 5-branes and ${\mathrm{SU}(2)}_{L}$ with another intersecting set of 5-branes is examined, and the cancellation phenomena is studied over the parameter space of the model. Large values of ${\ensuremath{\theta}}_{B}$ (the phase of B at the electroweak scale) can be accommodated, though again ${\ensuremath{\theta}}_{0B}$ must be fine-tuned. Using the conventional prescription for calculating ${d}_{n},$ one finds the region in parameter space where the experimental EDM constraints on both ${d}_{e}$ and ${d}_{n}$ hold is significantly reduced, and generally requires $\mathrm{tan}\ensuremath{\beta}\ensuremath{\lesssim}5$ for most of the parameter space, though there are small allowed regions even for $\mathrm{tan}\ensuremath{\beta}\ensuremath{\gtrsim}10.$ We find that the Weinberg three gluon term generally makes significant contributions, and the results are sensitive to the values of the quark masses.