arXiv subjects

Xin Cao

Publications and source records attributed to Xin Cao.

76 records · Page 5Linked to original sources

arXiv2017

Failure to replicate long-range tunable attractions in colloidal system

Recently, a temperature-sensitive long-range attraction colloidal system exhibiting melting and pre-melting of colloidal crystals has been reported by Li et al.[1]. If it is true, it would be an ideal system to simulate a board range of phase transitions happening in atomic systems. We have reanalyzed their data in [1] and have discovered great inconsistency in their radial distribution functions g(r) and pair potentials u(r). We have tried to reproduce their experimental results but failed to find the temperature-sensitive long rang attraction as reported by Li et al. Based on our experimental observations, We conclude that the melting and premelting reported in their paper are non-equilibrium phenomena caused by non-uniform temperature in the samples of Li et al..

cond-mat.soft↗

arXiv2016

Surface relaxation of vapour-depositing colloidal glasses

Vapour deposition can directly produce ultrastable glasses, which are similar to conventional glasses aged over thousands of years. The highly mobile surface layer is believed to accelerate the ageing process of vapour-deposited glasses, but its microscopic kinetics has not been experimentally observed. Here we studied the deposition growth kinetics of a two-dimensional colloidal glass at the single-particle level using video microscopy. We found that newly deposited particles in the surface layer (depth $d<14$ particles) relaxed via frequent out-of-cage motions, while particles in the deeper middle layer ($14<d\lesssim100$ particles) relaxed via activation of cooperative rearrangement regions (CRRs). These CRRs were much larger, more anisotropic and occurred more frequently than CRRs in the bulk ($d\gtrsim100$ particles) or after deposition. Their centers of mass moved towards the surface, while the particles within moved towards the bulk, causing free-volume "bubbles" to move towards the surface to give a more compact bulk glass. This two-step relaxation in two surface layers is distinct from the previously assumed relaxation in one surface mobile layer

cond-mat.soft↗

arXiv2012

Keyword-aware Optimal Route Search

Identifying a preferable route is an important problem that finds applications in map services. When a user plans a trip within a city, the user may want to find "a most popular route such that it passes by shopping mall, restaurant, and pub, and the travel time to and from his hotel is within 4 hours." However, none of the algorithms in the existing work on route planning can be used to answer such queries. Motivated by this, we define the problem of keyword-aware optimal route query, denoted by KOR, which is to find an optimal route such that it covers a set of user-specified keywords, a specified budget constraint is satisfied, and an objective score of the route is optimal. The problem of answering KOR queries is NP-hard. We devise an approximation algorithm OSScaling with provable approximation bounds. Based on this algorithm, another more efficient approximation algorithm BucketBound is proposed. We also design a greedy approximation algorithm. Results of empirical studies show that all the proposed algorithms are capable of answering KOR queries efficiently, while the BucketBound and Greedy algorithms run faster. The empirical studies also offer insight into the accuracy of the proposed algorithms.

cs.DB↗

arXiv1998

The relation between the Toda hierarchy and the KdV hierarchy

Under three relations connecting the field variables of Toda flows and that of KdV flows, we present three new sequences of combination of the equations in the Toda hierarchy which have the KdV hierarchy as a continuous limit. The relation between the Poisson structures of the KdV hierarchy and the Toda hierarchy in continuous limit is also studied.

solv-int↗