The investigation of time-varying synchrony of EEG during sentence learning using wavelet analysis

The synchrony analysis has been used as a tool for the purpose of investigating how the cognitive processes take place between different brain regions when the specified learning task is going on. We propose a novel method based on the time-frequency representation for quantifying synchronization between two channel EEG with both temporal and spectral resolution. The presented method employed the wavelet transform for cross coherent spectral analysis of the EEG signals recorded during sentences recognizing and learning. The wavelet-coherent magnitude spectra provide the information indicating the degree of coherence and the cross-wavelet phase relation serves to indicate the direction of information flow between two EEG channels on different cortical regions. Real EEG recordings are collected based on a cognitive target. It is observed from both the magnitude spectra and phase of the wavelet coherence that there are obvious differences between the identification of both Chinese and English sentences. These are helpful for the research on the English study for Chinese students.published_or_final_versio

Piezoelectric dispenser based on a piezoelectric-metal-cavity actuator

Author name used in this publication: K. H. LamAuthor name used in this publication: C. L. SunAuthor name used in this publication: K. W. KwokAuthor name used in this publication: H. L. W. Chan2009-2010 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Global attractors for strongly damped wave equations with displacement dependent damping and nonlinear source term of critical exponent

In this paper the long time behaviour of the solutions of 3-D strongly damped wave equation is studied. It is shown that the semigroup generated by this equation possesses a global attractor in H_{0}^{1}(\Omega)\times L_{2}(\Omega) and then it is proved that this global attractor is a bounded subset of H^{2}(\Omega)\times H^{2}(\Omega) and also a global attractor in H^{2}(\Omega)\cap H_{0}^{1}(\Omega)\times H_{0}^{1}(\Omega)

Twisting of a Pristine α-Fe Nanowire: From Wild Dislocation Avalanches to Mild Local Amorphization.

The torsion of pristine α-Fe nanowires was studied by molecular dynamics simulations. Torsion-induced plastic deformation in pristine nanowires is divided into two regimes. Under weak torsion, plastic deformation leads to dislocation nucleation and propagation. Twisting-induced dislocations are mainly 12 screw dislocations in a -oriented nanowire. The nucleation and propagation of these dislocations were found to form avalanches which generate the emission of energy jerks. Their probability distribution function (PDF) showed power laws with mixing between different energy exponents. The mixing stemmed from simultaneous axial and radial dislocation movements. The power-law distribution indicated strongly correlated 'wild' dislocation dynamics. At the end of this regime, the dislocation pattern was frozen, and further twisting of the nanowire did not change the dislocation pattern. Instead, it induced local amorphization at the grip points at the ends of the sample. This "melting" generated highly dampened, mild avalanches. We compared the deformation mechanisms of twinned and pristine α-Fe nanowires under torsion

Acoustic Emission from Porous Collapse and Moving Dislocations in Granular Mg-Ho Alloys under Compression and Tension.

We identified heterogeneous Mg-Ho alloys as an ideal material to measure the most extensive acoustic emission spectra available. Mg-Ho alloys are porous and show a high density of dislocations, which slide under external tension and compression. These dislocations nucleate near numerous heterogeneities. Two mechanisms compete under external forcing in the structural collapse, namely collapsing holes and the movements of dislocations. Their respective fingerprints in acoustic emission (AE) measurements are very different and relate to their individual signal strengths. Porous collapse generates very strong AE signals while dislocation movements create more but weaker AE signals. This allows the separation of the two processes even though they almost always coincide temporarily. The porous collapse follows approximately mean-field behavior (ε = 1.4, τ' = 1.82, α = 2.56, x = 1.93, χ = 1.95) with mean field scaling fulfilled. The exponents for dislocation movement are greater (ε = 1.92, τ' = 2.44, α = 3.0, x = 1.7, χ = 1.42) and follows approximately the force integrated mean-field predictions. The Omori scaling is similar for both mechanisms. The Bath's law is well fulfilled for the porous collapse but not for the dislocation movements. We suggest that such 'complex' mixing behavior is dominant in many other complex materials such as (multi-) ferroics, entropic alloys and porous ferroelastics, and, potentially, homogeneous materials with the simultaneous appearance of different collapse mechanisms.We appreciate the support of the Natural Science Foundation of China (51320105014, 51621063) and 111 project 2.0 (BP2018008). EKHS is grateful to EPSRC (EP/P024904/1) and the Leverhulme trust (RPG-2012-564)

High sensitivity cymbal-based accelerometer

Author name used in this publication: Cheng-Liang SunAuthor name used in this publication: K. H. LamAuthor name used in this publication: S. H. ChoyAuthor name used in this publication: H. L. W. ChanAuthor name used in this publication: X.-Z. ZhaoAuthor name used in this publication: C. L. Choy2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Fabrication and characterization of Ni/P(VDF-TrFE) nanoscaled coaxial cables

Author name used in this publication: Kwo Ho LamAuthor name used in this publication: Cheng-Liang SunAuthor name used in this publication: Helen Lai Wa Chan2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Energy harvesting with piezoelectric drum transducer

Author name used in this publication: Kwok Ho LamAuthor name used in this publication: Cheng Liang SunAuthor name used in this publication: Kin Wing KwokAuthor name used in this publication: Helen Lai Wa ChanAuthor name used in this publication: Ming Sen GuoAuthor name used in this publication: Xing-Zhong Zhao2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Lead-free multilayer piezoelectric transformer

Author name used in this publication: K. H. LamAuthor name used in this publication: S. WangAuthor name used in this publication: C. L. SunAuthor name used in this publication: X. Z. Zhao2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe