Multi-kink topological terms and charge-binding domain-wall condensation induced symmetry-protected topological states: Beyond Chern-Simons/BF theory

Quantum-disordering a discrete-symmetry breaking state by condensing domain-walls can lead to a trivial symmetric insulator state. In this work, we show that if we bind a 1D representation of the symmetry (such as a charge) to the intersection point of several domain walls, condensing such modified domain-walls can lead to a non-trivial symmetry-protected topological (SPT) state. This result is obtained by showing that the modified domain-wall condensed state has a non-trivial SPT invariant -- the symmetry-twist dependent partition function. We propose two different kinds of field theories that can describe the above mentioned SPT states. The first one is a Ginzburg-Landau-type non-linear sigma model theory, but with an additional multi-kink domain-wall topological term. Such theory has an anomalous $U^k(1)$ symmetry but an anomaly-free $Z_N^k$ symmetry. The second one is a gauge theory, which is beyond Abelian Chern-Simons/BF gauge theories. We argue that the two field theories are equivalent at low energies. After coupling to the symmetry twists, both theories produce the desired SPT invariant.Comment: 22 pages, 8 figures, symmetry transformaition for the Ginzburg-Landau NL$\sigma$M is added in the introduction part, references adde

Adamantane-1-ammonium benzoate

In the title molecular salt, C10H15NH3 +·C7H5O2 −, both carboxyl O atoms act as acceptors for strong N—H⋯O inter­molecular hydrogen-bond inter­actions with the ammonium group in the cation, generating infinite chains along the b axis. A weak C—H⋯π inter­action is also present

A Regularized Opponent Model with Maximum Entropy Objective

In a single-agent setting, reinforcement learning (RL) tasks can be cast into an inference problem by introducing a binary random variable o, which stands for the "optimality". In this paper, we redefine the binary random variable o in multi-agent setting and formalize multi-agent reinforcement learning (MARL) as probabilistic inference. We derive a variational lower bound of the likelihood of achieving the optimality and name it as Regularized Opponent Model with Maximum Entropy Objective (ROMMEO). From ROMMEO, we present a novel perspective on opponent modeling and show how it can improve the performance of training agents theoretically and empirically in cooperative games. To optimize ROMMEO, we first introduce a tabular Q-iteration method ROMMEO-Q with proof of convergence. We extend the exact algorithm to complex environments by proposing an approximate version, ROMMEO-AC. We evaluate these two algorithms on the challenging iterated matrix game and differential game respectively and show that they can outperform strong MARL baselines.Comment: Accepted to International Joint Conference on Artificial Intelligence (IJCA2019

Tensile behaviour of FRP grid strengtheneing ECC composite under a uniaxial loading

As the fibre reinforced polymer (FRP) sheets/textiles strengthening the inorganic cementitious materials technique was presented by some researchers, a few of potential shortcomings, such as penetrating difficultly of cementitious materials to and much brittle of FRP sheets, have been found in recent years. Therefore, a new strengthening system, which was FRP grid strengthening ECC system, in combination with the Engineered Cementitious Composites (ECC) and FRP grid was proposed by the present authors. By applying this system to reinforce the reinforced concrete (RC) beams, the dual strengthening effects can be provided and the intermediate crack-induced debonding failure can also be suppressed by externally bonded the FRP gird reinforced ECC composite layer to the tensile surface of the original RC beams. To investigate the tensile mechanical behaviour of FRP gird reinforced ECC composite layer, six non-strengthened ECC specimens and eighteen basalt fibre reinforced polymer grid (BFRP) strengthening ECC composite specimens (FRP-ECC specimens) subjected to the unidirectional axial tensile loading were conducted in this paper. Three kinds of different thickness BFRP grid were applied to investigate their reinforcement effects. The test results showed that there was no slip at the interface of BFRP grid and ECC substrate significantly. The failure modes were the internal PVA fibers ruptured or pulled out from ECC substrate for the non-strengthened ECC specimens and the rupture of BFRP reinforcements of grid for the strengthened FRP-ECC specimens. The axial stiffness of FRPECC specimens and the ultimate tensile stress and strain were obviously increased after the ECC substrate cracked, which indicated the contribution of the internal BFRP grid reinforcements. Moreover, an analytical model was also presented to predict the stress-strain relationship and the tensile strength of the FRP-ECC specimens and validated through comparison with the rest results

Seismicity Enhances Macrodispersion in Finite Porous and Fractured Domains: A Pore-Scale Perspective

Understanding the effects of oscillating flow field induced by seismicity on the transport process is vital for predicting the fate and transport of solute in many dynamic environments. However, there is prominent discrepancy in arguing with the response of dispersion to the oscillating flow field (i.e., the longitudinal dispersion coefficient would decrease, increase, or maintain unchanged). To unravel the underpinning physics about this controversial response, we simulated two-hundred twenty pore-scale numerical experiments for the seismicity-induced oscillating flow field and associated solute transport in the idealized finite porous (i.e., fluidic plate) and fractured (i.e., parallel plates) domains. The numerically obtained breakthrough curves were fitted to the macroscopic advection-dispersion equation to retrieve the mean velocity and apparent macrodispersion coefficient (DL). We found that DL increases to its maxima when the oscillating flow field resonates with the finite systems, that is, the period (T) of the oscillating flow field or the seismic wave approaches the pore volume (τ) of a finite domain. The resonant effects diminish and DL barely changes when T is much larger or smaller than τ. Moreover, the degree of enhancement in DL increases exponentially with the amplitude of the seismic force. Fundamental understanding of the response of macrodispersion to the oscillating flow field adds value in predicting the fate of solute in transient flow systems via the advection-dispersion equation