arXiv subjects

Zhao Wang

Publications and source records attributed to Zhao Wang.

At least 199 records · Page 11Linked to original sources

arXiv2019

Personality and Behavior in Role-based Online Games

Both offline and online human behaviors are affected by personality. Of special interests are online games, where players have to impersonate specific roles and their behaviors are extensively tracked by the game. In this paper, we propose to study the relationship between players' personality and game behavior in League of Legends (LoL), one of the most popular Multiplayer Online Battle Arena (MOBA) games. We use linear mixed effects (LME) models to describe relationships between players' personality traits (measured by the Five Factor Model) and two major aspects of the game: the impersonated roles and in-game actions. On the one hand, we study relationships within the game environment by modeling role attributes from match behaviors and vice versa. On the other hand, we analyze the relationship between a player's five personality traits and their game behavior by showing significant correlations between each personality trait and the set of corresponding behaviors. Our findings suggest that personality and behavior are highly entangled and provide a new perspective to understand how personality can affect behavior in role-based online games.

cs.HC↗

arXiv2019

On the $g$-extra connectivity of graphs

Connectivity and diagnosability are two important parameters for the fault tolerant of an interconnection network $G$. In 1996, Fàbrega and Fiol proposed the $g$-extra connectivity of $G$. A subset of vertices $S$ is said to be a \emph{cutset} if $G-S$ is not connected. A cutset $S$ is called an \emph{$R_g$-cutset}, where $g$ is a non-negative integer, if every component of $G-S$ has at least $g+1$ vertices. If $G$ has at least one $R_g$-cutset, the \emph{$g$-extra connectivity} of $G$, denoted by $κ_g(G)$, is then defined as the minimum cardinality over all $R_g$-cutsets of $G$. In this paper, we first obtain the exact values of $g$-extra connectivity of some special graphs. Next, we show that $1\leq κ_g(G)\leq n-2g-2$ for $0\leq g\leq \left\lfloor \frac{n-3}{2}\right\rfloor$, and graphs with $κ_g(G)=1,2,3$ and trees with $κ_g(T_n)=n-2g-2$ are characterized, respectively. In the end, we get the three extremal results for the $g$-extra connectivity.

math.CO↗

arXiv2019

Size effect on the spontaneous coalescence of nanowires

This paper investigates the size effect on the coalescence process of contacting nanoparticles. It is revealed by molecular dynamics that the nanometer-sized surface curvature coupled with the effective melting temperature exhibits a strong influence on the atom diffusion at the interface, and is therefore critical to the coalescence time. This effect is particularly pronouncing for surface curvatures below 20 nm. A phenomenological model is derived from the melting-point reduction approach to describe the kinetic process of nanowire coalescence and is validated against a variety of simulation datasets. The quantitative correlation between the sample size, the sintering temperature and the contact morphology evolution is demonstrated.

cond-mat.mtrl-sci↗

arXiv2019

Discovery of voltage induced superfluid-like penetration effect in liquid metals at room temperature

We have discovered that room temperature liquid metal is capable of penetrating through macro- and microporous materials by applying a voltage. In this work, we demonstrate the liquid metal penetration effect in various porous materials such as tissue paper, thick and fine sponges, fabrics, and meshes. The penetration effect mimics one of the three well-known superfluid properties of liquid helium superfluid that only occur at near-zero Kelvin. The underlying mechanism is that the high surface tension of liquid metal can be significantly reduced to near-zero due to the voltage induced oxidation of the liquid metal surface in a solution. It is the extremely low surface tension and gravity that cause the liquid metal to superwet the solid surface, leading to the penetration phenomena. Our findings offer new opportunities for novel microfluidic applications and could promote further discovery of more exotic fluid states of liquid metals.

cond-mat.other↗

arXiv2019

One possible explanation for earthquake occurrences from anomalous line-of-sight propagations in the very high frequency band by fast Fourier transform spectral analysis

This paper illustrated the possible relationship between the occurrences of the earthquake and the anomalous line-of-sight propagations in the very high frequency band by the fast Fourier transform spectral analysis. Despite many anomalous propagations appear in the different very high frequency band during the earthquake occurrences, the majority of these abnormal signals contain similar frequency distributions in the frequency domain. For the 31 anomalous propagation spectral distributions, 30 of them present the same curve peaks, within a frequency range of (0-0.5)Hz. Furthermore, for the first time, we found that the spectral maximum of all anomalous propagations are below the characteristic Brunt-Vaisala frequency (period T larger than 6 min), which happens to be the frequency range of the internal gravity waves, which might evidence that the atmospheric gravity waves should be responsible for the indirect coupling between lithosphere and ionosphere. These novel results might provide direct evidence to the relationship between the anomalous propagations in the very high frequency band and the occurrences of earthquakes.

physics.geo-ph↗

arXiv2019

First-principle study on the electronic and optical properties of cavities occupancy of SI methane hydrates

The electronic density of state and optical properties of the SI methane hydrates with three different configurations are calculated by first-principle, including (abbreviated as cI, similarly hereinafter), each cage is fully filled with only one methane molecule; (cII), only one of the small cage lacks its unique methane molecule; (cIII), only one large cage lacks its unique methane molecule. The results show that the hydrate is most stable in the cI due to its perfect structure, the cII is less stable, whereas the cIII is least stable owing to its larger structural distortion after the loss of methane. On the contrary, loss of a methane from cII causes negligible deformation. The electronic density of states and the energy band gap of the cII is almost the same with those of cI, differing obviously with those of cIII. Methane hydrate is only responsive to light in the ultraviolet region, revealing their similar properties, regardless of their structural discrepancies, or/and the different ratios of water and methane molecules, 46/8=5.75 versus 46/7=6.57. Our calculations demonstrate that the lack of one methane in the cII causes negligible influence to the lattice structure and therefore to the electronic and optical properties in comparison with the cI, whereas the lack of one methane in the cIII can cause detectable changes. These results might provide valuable reference to the industrial exploration.

cond-mat.mtrl-sci↗

arXiv2019

Gallai-Ramsey numbers for fans

Given a graph $G$ and a positive integer $k$, define the \emph{Gallai-Ramsey number} to be the minimum number of vertices $n$ such that any $k$-edge coloring of $K_n$ contains either a rainbow (all different colored) triangle or a monochromatic copy of $G$. In this paper, we obtain general upper and lower bounds on the Gallai-Ramsey numbers for fans $F_{m} = K_{1} + mK_{2}$ and prove the sharp result for $m = 2$ and for $m = 3$ with $k$ even.

math.CO↗

arXiv2019

A complete data processing workflow for CryoET and subtomogram averaging

Electron cryotomography (CryoET) is currently the only method capable of visualizing cells in 3D at nanometer resolutions. While modern instruments produce massive amounts of tomography data containing extremely rich structural information, the data processing is very labor intensive and results are often limited by the skills of the personnel rather than the data. We present an integrated workflow that covers the entire tomography data processing pipeline, from automated tilt series alignment to subnanometer resolution subtomogram averaging. This workflow greatly reduces human effort and increases throughput, and is capable of determining protein structures at state-of-the-art resolutions for both purified macromolecules and cells.

q-bio.QM↗

arXiv2018

When do Words Matter? Understanding the Impact of Lexical Choice on Audience Perception using Individual Treatment Effect Estimation

Studies across many disciplines have shown that lexical choice can affect audience perception. For example, how users describe themselves in a social media profile can affect their perceived socio-economic status. However, we lack general methods for estimating the causal effect of lexical choice on the perception of a specific sentence. While randomized controlled trials may provide good estimates, they do not scale to the potentially millions of comparisons necessary to consider all lexical choices. Instead, in this paper, we first offer two classes of methods to estimate the effect on perception of changing one word to another in a given sentence. The first class of algorithms builds upon quasi-experimental designs to estimate individual treatment effects from observational data. The second class treats treatment effect estimation as a classification problem. We conduct experiments with three data sources (Yelp, Twitter, and Airbnb), finding that the algorithmic estimates align well with those produced by randomized-control trials. Additionally, we find that it is possible to transfer treatment effect classifiers across domains and still maintain high accuracy.

cs.LG↗

arXiv2018

Understanding Phonon Scattering by Nano-Precipitates in Potassium-Doped Lead Chalcogenides

We present a comprehensive experimental and theoretical study of phonon scattering by nanoprecipitates in potassium-doped PbTe, PbSe and PbS. We highlight the role of the precipitate size distribution measured by microscopy, whose tuning allows for thermal conductivities lower than the limit achievable with a single size. The correlation between the size distribution and the contributions to thermal conductivity from phonons in different frequency ranges provides a physical basis to the experimentally measured thermal conductivities, and a criterion to estimate the lowest achievable thermal conductivity. The results have clear implications for efficiency enhancements in nanostructured bulk thermoelectrics.

cond-mat.mtrl-sci↗

arXiv2018

An atomistic model for the charge distribution in layered MoS2

We present an atomistic model for predicting the distribution of doping electric charges in layered molybdenum disulfide (MoS$_{2}$). This model mimics the charge around each ion as a net Gaussian-spatially-distributed charge plus an induced dipole, and is able to predict the distribution of doping charges in layered MoS$_{2}$ in a self-consistent scheme. The profiles of doping charges in monolayer MoS$_{2}$ flakes computed by this charge-dipole model are in good agreement with those obtained by density-functional-theory calculations. Using this model, we quantitatively predict the charge enhancement effect in MoS$_{2}$ monolayer nanoribbons, with which strong ionic charge-localization effects are shown.

cond-mat.mes-hall↗

arXiv2018

Lubricity of graphene on rough Au surfaces

This paper studies the lubricating properties of graphene on randomly rough Au surfaces in sliding nanofriction using molecular dynamics. It is shown that the friction and the consequent heat dissipation decrease more than an order of magnitude in the presence of graphene. The performance of graphene nanoribbons as lubricants is, however, limited because of detachment and displacement at the interface. Sliding contacts lubricated with a stretched graphene sheet exhibit low friction, but possibly also low structural stability. This suggests that the graphene-substrate adherence could be crucial for the lubricity of two-dimensional materials on rough metal surfaces.

cond-mat.mtrl-sci↗

arXiv2018

Steiner Distance in Product Networks

For a connected graph $G$ of order at least $2$ and $S\subseteq V(G)$, the \emph{Steiner distance} $d_G(S)$ among the vertices of $S$ is the minimum size among all connected subgraphs whose vertex sets contain $S$. Let $n$ and $k$ be two integers with $2\leq k\leq n$. Then the \emph{Steiner $k$-eccentricity $e_k(v)$} of a vertex $v$ of $G$ is defined by $e_k(v)=\max \{d_G(S)\,|\,S\subseteq V(G), \ |S|=k, \ and \ v\in S\}$. Furthermore, the \emph{Steiner $k$-diameter} of $G$ is $sdiam_k(G)=\max \{e_k(v)\,|\, v\in V(G)\}$. In this paper, we investigate the Steiner distance and Steiner $k$-diameter of Cartesian and lexicographical product graphs. Also, we study the Steiner $k$-diameter of some networks.

math.CO↗

arXiv2018

Decentralized Caching Schemes and Performance Limits in Two-layer Networks

We study the decentralized caching scheme in a two-layer network, which includes a sever, multiple helpers, and multiple users. Basically, the proposed caching scheme consists of two phases, i.e, placement phase and delivery phase. In the placement phase, each helper/user randomly and independently selects contents from the server and stores them into its memory. In the delivery phase, the users request contents from the server, and the server satisfies each user through a helper. Different from the existing caching scheme, the proposed caching scheme takes into account the pre-stored contents at both helpers and users in the placement phase to design the delivery phase. Meanwhile, the proposed caching scheme exploits index coding in the delivery phase and leverages multicast opportunities, even when different users request distinct contents. Besides, we analytically characterize the performance limit of the proposed caching scheme, and show that the achievable rate region of the proposed caching scheme lies within constant margins to the information-theoretic optimum. In particular, the multiplicative and additive factors are carefully sharpened to be $\frac{1}{48}$ and $4$ respectively, both of which are better than the state of arts. Finally, simulation results demonstrate the advantage of the proposed caching scheme compared with the state of arts.

cs.IT↗

arXiv2018

Ramsey and Gallai-Ramsey numbers for two classes of unicyclic graphs

Given a graph $G$ and a positive integer $k$, define the \emph{Gallai-Ramsey number} to be the minimum number of vertices $n$ such that any $k$-edge coloring of $K_n$ contains either a rainbow (all different colored) triangle or a monochromatic copy of $G$. In this paper, we consider two classes of unicyclic graphs, the star with an extra edge and the path with a triangle at one end. We provide the $2$-color Ramsey numbers for these two classes of graphs and use these to obtain general upper and lower bounds on the Gallai-Ramsey numbers.

math.CO↗

arXiv2018

A Unified Gas-kinetic Scheme for Continuum and Rarefied Flows VI: Dilute Disperse Gas-Particle Multiphase System

In this paper, a unified gas kinetic scheme for multiphase dilute gas-particle system is proposed. The UGKS multiphase (UGKS-M) is a finite volume method, which captures flow physics in the regimes from collisionless multispecies transport to the two-fluid hydrodynamic Navier-Stokes (NS) solution with the variation of Knudsen number, and from granular flow regime to dusty gas dynamics with the variation of Stokes number. The main reason for preserving the multiscale nature in UGKS-M is mainly coming from the direct modeling of the flow physics in the scales of discrete cell size and time step, where the ratio of the time step over the particle collision time determines flow behavior in different regimes. For the particle phase, the integral solution of the kinetic equation is used in the construction of the numerical flux, which takes into account the particle transport, collision, and acceleration. The gas phase, which is assumed to be in the continuum flow regime, evolves numerically by the gas kinetic scheme (GKS), which is a subset of the UGKS for the Navier-Stokes (NS) solutions. The interaction between the gas and particle phase is calculated based on a velocity space mapping method, which solves accurately the kinetic acceleration process. The stability of UGKS-M is determined by the CFL condition only. With the inclusion of the material temperature evolution equation of solid particles, the UGKS-M conserves the total mass, momentum, and energy for the whole multiphase system. In the numerical tests, the UGKS-M shows good multiscale property in capturing the particle trajectory crossing (PTC), particle wall reflecting phenomena, and vortex-induced segregation of inertial particles under different Stokes numbers. The scheme is also applied to simulate shock induced fluidization problem and the simulation results agree well with experimental measurement.

physics.comp-ph↗

arXiv2018

Matching preclusion number of graphs

The \emph{matching preclusion number} of a graph $G$, denoted by $\mpo(G)$, is the minimum number of edges whose deletion results in a graph that has neither perfect matchings nor almost-perfect matchings. In this paper, we first give some sharp upper and lower bounds of matching preclusion number. Next, graphs with large and small matching preclusion number are characterized, respectively. In the end, we investigate some extremal problems and the Nordhaus-Gaddum-type relations on matching preclusion number.

math.CO↗

arXiv2018

Gallai-Ramsey numbers for books

Given a graph $G$ and a positive integer $k$, the \emph{Gallai-Ramsey number} is defined to be the minimum number of vertices $n$ such that any $k$-edge coloring of $K_n$ contains either a rainbow (all different colored) triangle or a monochromatic copy of $G$. In this paper, we obtain general upper and lower bounds on the Gallai-Ramsey numbers for books $B_{m} = K_{2} + \overline{K_{m}}$ and prove sharp results for $m \leq 5$.

math.CO↗