arXiv subjects

Jia Zhou

Publications and source records attributed to Jia Zhou.

66 records · Page 4Linked to original sources

arXiv2020

Observation of contact angle hysteresis due to inhomogeneous electric fields

Static contact angle hysteresis (CAH) is widely attributed to surface roughness and chemical contamination. In the latter case, chemical defects create free-energy barriers that prevent the contact line motion. Electrowetting studies have demonstrated the similar ability of electric fields to alter the surface free-energy landscape. Yet, the increase of apparent static CAH by electric fields remains unseen. Here, we report the observation and theoretical analysis of electrowetting hysteresis. This phenomenon enables the continuous and dynamic control of CAH, not only for fundamental studies but also to manufacture sticky-on-demand surfaces for sample collection.

physics.flu-dyn↗

arXiv2020

Constraining isovector nuclear interactions with giant resonances within a Bayesian approach

We put a stringent constraint on the isovector nuclear interactions in the Skyrme-Hartree-Fock model from the centroid energy $E_{-1}$ of the isovector giant dipole resonance in $^{208}$Pb as well as its electric polarizability $α_D$. Using the Bayesian analysis method, $E_{-1}$ and $α_D$ are found to be mostly determined by the nuclear symmetry energy $E_{sym}$ at about $ρ^\star=0.05$ fm$^{-3}$ and the isovector nucleon effective mass $m_v^\star$ at the saturation density. At $90\%$ confidence level, we obtain $E_{sym}(ρ^\star) = 16.4 ^{+1.0}_{-0.9}$ MeV and $m_v^\star/m = 0.79 ^{+0.06}_{-0.06}$.

nucl-th↗

arXiv2019

On-demand contact line pinning during droplet evaporation

Depending on the contact line motion, colloid-rich drolets evaporation can leave a ring-like or a spot-like residue. Herein, we determine this outcome by controlling the contact line motion using coplanar direct current electrowetting-on-dielectrics (DC-EWOD). Combined with theoretical calculations of the droplet shape and its evaporation rate, the time-dependent actuation voltage is first derived from experiments and simulations. Thanks to the additional control over the contact angle, the contact line can be maintained in pinned state even on surfaces that exhibit little contact angle hysteresis such as homogenous flat Teflon coatings. In the absence of EWOD control, polystyrene particles and Escherichia coli suspended in the droplet formed a dot-like pattern at the center of the initial contact, whereas application of the mechanism resulted in ring-like patterns of a controllable radius. Unlike chemically or structurally patterned substrates, the contact line could recover its mobility at any preset time before reaching the control limit, which is useful to accurately and consistently fabricate self-assembled nanostructures of desired patterns on different surfaces.

physics.flu-dyn↗

arXiv2019

Trajectory of particles exposed to a tilted-angle washboard potential: application to high-throughput acoustophoresis in microchannels

A wide variety of tilted washboard potentials based on acoustic waves, electric fields, optical patterns and so on have been applied to sort particles in microchannels. In this paper, we present a theoretical analysis of the particles trajectory in a washboard potential making a tilt angle $θ$ with the flow. Depending on the sorting to drag force ratio $ε$, we identified a transition threshold $ε= \cos(θ)$ between two distinct regimes of particles motion: drift and locked modes. In drift mode, the particles follow an oscillating trajectory which slope is given by $\frac{ε^2}{2}\tan(θ)$, while in locked mode the trajectory slope is given by $1/\tan(θ)$. These theoretical predictions agree quantitatively well with previously published experimental data and may help in the design of high-performance microfluidic sorting devices.

physics.flu-dyn↗

arXiv2017

Study of weak corrections to Drell-Yan, top-quark pair and dijet Production at high energies with MCFM

Electroweak (EW) corrections can be enhanced at high energies due to the soft or collinear radiation of virtual and real $W$ and $Z$ bosons that result in Sudakov-like corrections of the form $α_W^l\log^n(Q^2/M_{W,Z}^2)$, where $α_W =α/(4π\sin^2θ_W)$ and $n\le 2l-1$. The inclusion of EW corrections in predictions for hadron colliders is therefore especially important when searching for signals of possible new physics in distributions probing the kinematic regime $Q^2 \gg M_V^2$. Next-to-leading order (NLO) EW corrections should also be taken into account when their size ($\mathcal{O}(α)$) is comparable to that of QCD corrections at next-to-next-to-leading order (NNLO) ($\mathcal{O}(α_s^2)$). To this end we have implemented the NLO weak corrections to the Neutral-Current Drell-Yan process, top-quark pair production and di-jet production in the parton-level Monte-Carlo program MCFM. This enables a combined study with the corresponding QCD corrections at NLO and NNLO. We provide both the full NLO weak corrections and their Sudakov approximation since the latter is often used for a fast evaluation of weak effects at high energies and can be extended to higher orders. With both the exact and approximate results at hand, the validity of the Sudakov approximation can be readily quantified

hep-ph↗

arXiv2016

Triple Derivations and Triple Homomorphisms of Perfect Lie Superalgebras

In this paper, we study triple derivations and triple homomorphisms of perfect Lie superalgebras over a commutative ring $R$. It is proved that, if the base ring contains $\frac{1}{2}$, $L$ is a perfect Lie superalgebra with zero center, then every triple derivation of $L$ is a derivation, and every triple derivation of the derivation algebra $ Der (L)$ is an inner derivation. Let $L,~L^{'}$ be Lie superalgebras over a commutative ring $R$, the notion of triple homomorphism from $L$ to $L^{'}$ is introduced. We proved that, under certain assumptions, homomorphisms, anti-homomorphisms, and sums of homomorphisms and anti-homomorphisms are all triple homomorphisms.

math.RA↗

arXiv2015

Electroweak Corrections at the LHC with MCFM

Electroweak (EW) corrections at the LHC can be enhanced at high energies due to soft/collinear radiation of W and Z bosons, being dominated by Sudakov-like corrections in the form of $α_W^l\log^n(Q^2/M_W^2)$ $(n \le 2l, α_W = α/(4π\sinθ_W^2))$ when the energy scale $Q$ enters the TeV regime. Thus, the inclusion of EW corrections in LHC predictions is important for the search of possible signals of new physics in tails of kinematic distributions. EW corrections should also be taken into account in virtue of their comparable size ($\mathcal{O}(α)$) to that of higher order QCD corrections ($\mathcal{O}(α_s^2)$). We calculated the next-to-leading-order (NLO) weak corrections to the neutral-current (NC) Drell-Yan process, top-quark pair production and di-jet producion, and implemented them in the Monte-Carlo program MCFM. This enables a combined study with the corresponding NLO QCD corrections. We provide both the full NLO weak corrections and their weak Sudakov approximation valid at high energies. The latter is often used for a fast evaluation of weak effects, and having the exact result available as well allows to quantify the validity of the Sudakov approximation.

hep-ph↗

arXiv2014

Generalized Derivations of Lie triple systems

In this paper, we present some basic properties concerning the derivation algebra ${\rm Der}(T)$, the quasiderivation algebra ${\rm QDer}(T)$ and the generalized derivation algebra ${\rm GDer}(T)$ of a Lie triple system $T$, with the relationship ${\rm Der}(T)\subseteq {\rm QDer}(T)\subseteq {\rm GDer}(T)\subseteq {\rm End}(T)$. Furthermore, we completely determine those Lie triple systems $T$ with condition ${\rm QDer}(T)={\rm End}(T)$. We also show that the quasiderivations of $T$ can be embedded as derivations in a larger Lie triple system.

math.RA↗

arXiv2014

Sparse Graph-based Transduction for Image Classification

Motivated by the remarkable successes of Graph-based Transduction (GT) and Sparse Representation (SR), we present a novel Classifier named Sparse Graph-based Classifier (SGC) for image classification. In SGC, SR is leveraged to measure the correlation (similarity) of each two samples and a graph is constructed for encoding these correlations. Then the Laplacian eigenmapping is adopted for deriving the graph Laplacian of the graph. Finally, SGC can be obtained by plugging the graph Laplacian into the conventional GT framework. In the image classification procedure, SGC utilizes the correlations, which are encoded in the learned graph Laplacian, to infer the labels of unlabeled images. SGC inherits the merits of both GT and SR. Compared to SR, SGC improves the robustness and the discriminating power of GT. Compared to GT, SGC sufficiently exploits the whole data. Therefore it alleviates the undercomplete dictionary issue suffered by SR. Four popular image databases are employed for evaluation. The results demonstrate that SGC can achieve a promising performance in comparison with the state-of-the-art classifiers, particularly in the small training sample size case and the noisy sample case.

cs.CV↗

arXiv2014

Generalized Derivations of Hom-Lie Superalgebras

In this paper, we give some basic properties of the generalized derivation algebra ${\rm GDer}(L)$ of a Hom-Lie superalgebra $L$. In particular, we prove that ${\rm GDer}(L) = {\rm QDer}(L) + {\rm QC}(L)$, the sum of the quasiderivation algebra and the quasicentroid. We also prove that ${\rm QDer}(L)$ can be embedded as derivations in a larger Hom-Lie superalgebra.

math.RA↗

arXiv2008

A preliminary analysis of the energy transfer between the dark sectors of the Universe

We study the mutual interaction between the dark sectors (dark matter and dark energy) of the Universe by resorting to the extended thermodynamics of irreversible processes and constrain the former with supernova type Ia data. As a byproduct, the present dark matter temperature results in good agreement with independent estimates of the temperature of the gas of sterile neutrinos.

gr-qc↗

arXiv2007

The generalized second law of thermodynamics in the accelerating universe

We show that in the accelerating universe the generalized second law of thermodynamics holds only in the case where the enveloping surface is the apparent horizon, but not in the case of the event horizon. The present analysis relies on the most recent SNe Ia events, being model independent. Our study might suggest that event horizon is not a physical boundary from the point of view of thermodynamics.

gr-qc↗