173 research outputs found
When Speech Totally Fails, Resistance Takes Place: With Special Reference to Youth Resistance in China
Social harmony depends on the citizens’ prosocial attitudes and behaviors that presuppose people’s high eudaimonic living, where individuals tend to pursue intrinsic goals and values, behave autonomously, volitionally or consensually, and show mindfulness. Nevertheless, such harmony is the optimal state of public administration (yet never easily attainable), for the smooth and harmonious running of social life is interrupted at intervals throughout history in almost any society, in the form of various sorts of resistance: conjunct complaints, strikes, sit-ins, demonstrations, riots and uprisings/revolutions. Just as more and more societies claim to have entered the post-modern era, which is characterized by eudaimonic living in terms of surplus material supply rather than poverty, pan-entertainment rather than somberness, information explosion rather than data shortage, they have to address the old-fashioned embarrassing ailment again: a series of unsettling youth resistance movements that currently are looming worldwide. Applying cultural theories on speech right, with focus on youth resistance, especially that in contemporary China since 1989, we find: a) default of effective speech/articulation, the not-yet-in-power youth tend to launch resistance motivated by two causes: the deterioration of living (especially due to oppressive corruptions), and/or the perception of the deterioration of the social system which indicates loss of hope; b) the solution lies in the acceptance of the rationality underlying such non-discursive collective “representation”: affordable amelioration of their living for the first type; for the far more complicated second type, incorporation of their appeals to avoid continuing subversive mobilizations and movements. While effective discursive channel of articulation contributes to release of indignation and elimination of the powder-keg effect, hence an ideal solution to all sorts of resistance, in information era such articulation channel should be open to the youth who is ascendant in IT competence
Finite bending and pattern evolution of the associated instability for a dielectric elastomer slab
We investigate the finite bending and the associated bending instability of
an incompressible dielectric slab subject to a combination of applied voltage
and axial compression, using nonlinear electro-elasticity theory and its
incremental version. We first study the static finite bending deformation of
the slab. We then derive the three-dimensional equations for the onset of
small-amplitude wrinkles superimposed upon the finite bending. We use the
surface impedance matrix method to build a robust numerical procedure for
solving the resulting dispersion equations and determining the wrinkled shape
of the slab at the onset of buckling. Our analysis is valid for dielectrics
modeled by a general free energy function. We then present illustrative
numerical calculations for ideal neo-Hookean dielectrics. In that case, we
provide an explicit treatment of the boundary value problem of the finite
bending and derive closed-form expressions for the stresses and electric field
in the body. For the incremental deformations, we validate our analysis by
recovering existing results in more specialized contexts. We show that the
applied voltage has a destabilizing effect on the bending instability of the
slab, while the effect of the axial load is more complex: when the voltage is
applied, changing the axial loading will influence the true electric field in
the body, and induce competitive effects between the circumferential
instability due to the voltage and the axial instability due to the axial
compression. We even find circumstances where both instabilities cohabit to
create two-dimensional patterns on the inner face of the bent sector
Nonlinear response and axisymmetric wave propagation in functionally graded soft electro-active tubes
Soft electro-active (SEA) materials can be designed and manufactured with
gradients in their material properties, to modify and potentially improve their
mechanical response in service. Here, we investigate the nonlinear response of,
and axisymmetric wave propagation in a soft circular tube made of a
functionally graded SEA material and subject to several biasing fields,
including axial pre-stretch, internal/external pressure, and through-thickness
electric voltage. We take the energy density function of the material to be of
the Mooney-Rivlin ideal dielectric type, with material parameters changing
linearly along the radial direction. We employ the general theory of nonlinear
electro-elasticity to obtain explicitly the nonlinear response of the tube to
the applied fields. To study wave propagation under inhomogeneous biasing
fields, we formulate the incremental equations of motion within the state-space
formalism. We adopt the approximate laminate technique to derive the analytical
dispersion relations for the small-amplitude torsional and longitudinal waves
superimposed on a finitely deformed state. Comprehensive numerical results then
illustrate that the material gradients and biasing fields have significant
influences on the static nonlinear response and on the axisymmetric wave
propagation in the tube. This study lays the groundwork for designing SEA
actuators with improved performance, for tailoring tunable SEA waveguides, and
for characterizing non-destructively functionally graded tubular structures
Tunable morphing of electroactive dielectric-elastomer balloons
Designing smart devices with tunable shapes has important applications in
industrial manufacture. In this paper, we investigate the nonlinear deformation
and the morphological transitions between buckling, necking, and snap-through
instabilities of layered DE balloons in response to an applied radial voltage
and an inner pressure. We propose a general mathematical theory of nonlinear
electro-elasticity able to account for finite inhomogeneous strains provoked by
the electro-mechanical coupling. We investigate the onsets of morphological
transitions of the spherically symmetric balloons using the surface impedance
matrix method. Moreover, we study the nonlinear evolution of the bifurcated
branches through finite element numerical simulations. Our analysis
demonstrates the possibility to design tunable DE spheres, where the onset of
buckling and necking can be controlled by geometrical and mechanical properties
of the passive elastic layers. Relevant applications include soft robotics and
mechanical actuators
Causality-based Dual-Contrastive Learning Framework for Domain Generalization
Domain Generalization (DG) is essentially a sub-branch of out-of-distribution
generalization, which trains models from multiple source domains and
generalizes to unseen target domains. Recently, some domain generalization
algorithms have emerged, but most of them were designed with non-transferable
complex architecture. Additionally, contrastive learning has become a promising
solution for simplicity and efficiency in DG. However, existing contrastive
learning neglected domain shifts that caused severe model confusions. In this
paper, we propose a Dual-Contrastive Learning (DCL) module on feature and
prototype contrast. Moreover, we design a novel Causal Fusion Attention (CFA)
module to fuse diverse views of a single image to attain prototype.
Furthermore, we introduce a Similarity-based Hard-pair Mining (SHM) strategy to
leverage information on diversity shift. Extensive experiments show that our
method outperforms state-of-the-art algorithms on three DG datasets. The
proposed algorithm can also serve as a plug-and-play module without usage of
domain labels
Pattern evolution in bending dielectric-elastomeric bilayers
We propose theoretical and numerical analyses of smart bending deformation of
a dielectric-elastic bilayer in response to a voltage, based on the nonlinear
theory of electro-elasticity and the associated linearized incremental field
theory. We reveal that the mechanism allowing the bending angle of the bilayer
can be tuned by adjusting the applied voltage. Furthermore, we investigate how
much can the bilayer be bent before it loses its stability by buckling when one
of its faces is under too much compression. We find that the physical
properties of the two layers must be selected to be of the same order of
magnitude to obtain a consequent bending without encountering buckling. If
required, the wrinkles can be designed to appear on either the inner or the
outer bent surface of the buckled bilayer. We validate the results through
comparison with those of the classical elastic problem
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