Pore Characteristics and Computed Permeability of Pastes Subject to Freeze-thaw Cycles at Very Early Ages by X-ray CT

Freeze-thaw cycling can damage microstructure of concrete and reduce the service life of concrete structures. This is especially detrimental for concrete subject to freeze-thaw cycles at very early-ages, such as within the first few days after constructions. Typical low and high water-to-cement (w/c) ratio pastes are investigated experimentally and numerically in this study. The pastes are subject to freeze-thaw cycles at the age of 1, and 7 days and then sealed-cured to the age of 45 days. The pore size distribution is measured and quantified by X-ray computer tomography (CT) with high resolution. The permeability of the corresponding pastes is predicted numerically based on the reconstructed microstructure results obtained from the CT measurements. The pore size distribution and the permeability variations of different pastes are investigated, and the key affecting factors are recognized. The Katz-Thompson and Navier-Stokes methods for computing permeability of paste are compared. The detectable pore size range by MIP, BSE, and X-ray CT in hardened paste is identified. The results of this study will offer suggestions for material design and curing strategies for concrete structures which are prone to experiencing freeze-thaw cycles at very early-ages

The Effect of Mobile Gamification on Brand Loyalty

The purpose of this study is mainly to use the gamification concept to design a mobile gaming app (application) for contextual marketing, and we will integrate digital game design technologies, such as augmented reality (AR) and global positioning system (GPS). The study will then look at associated consumer value and brand loyalty created by the users after experiencing the mobile game. Accordingly, we define the eight elements of a mobile gamification design, including coping-escape, fantasy, recreation, social, omnipotence, competition, skill development, and location-based. This research model treats “location-based” as a formative second-order construct driven by ubiquitous connectivity and contextual offer. Consumer value and brand loyalty are also a second-order construct. The study will conduct a quasi-experimental research to verify our model. It is hoped that service managers can benefit from the insights discovered from this study and implement more effective management strategies for effective performance

Diversity Order Analysis for Quantized Constant Envelope Transmission

Quantized constant envelope (QCE) transmission is a popular and effective technique to reduce the hardware cost and improve the power efficiency of 5G and beyond systems equipped with large antenna arrays. It has been widely observed that the number of quantization levels has a substantial impact on the system performance. This paper aims to quantify the impact of the number of quantization levels on the system performance. Specifically, we consider a downlink single-user multiple-input-single-output (MISO) system with M-phase shift keying (PSK) constellation under the Rayleigh fading channel. We first derive a novel bound on the system symbol error probability (SEP). Based on the derived SEP bound, we characterize the achievable diversity order of the quantized matched filter (MF) precoding strategy. Our results show that full diversity order can be achieved when the number of quantization levels L is greater than the PSK constellation order M, i.e., L>M, only half diversity order is achievable when L=M, and the achievable diversity order is 0 when L<M. Simulation results verify our theoretical analysis.Comment: 9 pages, 3 figures, submitted for possible publicatio

Five-dimensional generalized f(R)f(R) gravity with curvature-matter coupling

The generalized $f(R)$ gravity with curvature-matter coupling in five-dimensional (5D) spacetime can be established by assuming a hypersurface-orthogonal spacelike Killing vector field of 5D spacetime, and it can be reduced to the 4D formulism of FRW universe. This theory is quite general and can give the corresponding results to the Einstein gravity, $f(R)$ gravity with both no-coupling and non-minimal coupling in 5D spacetime as special cases, that is, we would give the some new results besides previous ones given by Ref.\cite{60}. Furthermore, in order to get some insight into the effects of this theory on the 4D spacetime, by considering a specific type of models with $f_{1}(R)=f_{2}(R)=\alpha R^{m}$ and $B(L_{m})=L_{m}=-\rho$, we not only discuss the constraints on the model parameters $m$, $n$, but also illustrate the evolutionary trajectories of the scale factor $a(t)$, the deceleration parameter $q(t)$ and the scalar field $\epsilon(t)$, $\phi(t)$ in the reduced 4D spacetime. The research results show that this type of $f(R)$ gravity models given by us could explain the current accelerated expansion of our universe without introducing dark energy.Comment: arXiv admin note: text overlap with arXiv:0912.4581, arXiv:gr-qc/0411066 by other author