Search

Ordinary Portland cement, soil and foaming agent are the raw materials used to make soil-based foamed concrete. The effects of foam content and silica fume on the physical properties of [...]

Sodium silicate and promoters have been widely used as supplementary cementing materials substituting ordinary Portland cement to improve the properties of stabilized soils. In this paper, the developments of mechanical [...]

ABSTRACT In this article, a new type of graft copolymer retarder as modified phosphoaluminate cement (MPC) has been discussed. Graft copolymerization of 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and itaconic acid [...]

We study the holographic and agegraphic dark energy models without interaction using the latest observational Hubble parameter data, the Union 2.1 compilation of type Ia supernovae, and the energy conditions. Scenarios of dark energy are distinguished by the cutoff of cosmic age, conformal time, and event horizon. The best-fit value of matter density for the three scenarios almost steadily located at Ωm0=0.26 by the joint constraint. For the agegraphic models, they can be recovered to the standard cosmological model when the constant c which presents the fraction of dark energy approaches to infinity. Absence of the upper limit of c by the joint constraint demonstrates the recovery possibility. Using the fitted result, we also reconstruct the current equation of state of dark energy at different scenarios, respectively. Employing the model criteria χmin²/dof, we find that conformal time model is the worst, but they cannot be distinguished clearly. Comparing with the observational constraints, we find that the strong energy condition is fulfilled at redshift 0.2≲z≲0.3 with 1s confidence level. We also find that the null energy condition gives a meaningful constraint for the event horizon cutoff model, especially compared with observational Hubble parameter data only. We note that the energy condition maybe could play an important role in the interacting models because of different degeneracy between Ωm and constant c. [ABSTRACT FROM AUTHOR]

Solvent extraction technique was performed to optimize the conditions for maximum removal of iron (III) from the simulated bauxite hydrochloric acid leaching liquor of FeCl3+AlCl3+CaCl2+HCl. Some factors influencing the extraction, such as the extractant and concentration of Fe, Al, and Ca were investigated. The results indicated that the N235 is an effective extractant for selective extraction of iron (III) from chloride liquor. The concentration of Fe in raffinate is under 0.0165 gL-1 and the losing of Al is 0.50 % by N235.

We use simulated Hubble parameter data in the redshift range 0 [?] z [?] 2 to explore the role and power of observational H(z) data in constraining cosmological parameters of the LCDM model. The error model of the simulated data is empirically constructed from available measurements and scales linearly as z increases. By comparing the median figures of merit calculated from simulated data sets with that of current Type Ia supernova (SNIa) data, we find that as many as 64 further independent measurements of H(z) are needed to match the parameter constraining power of SNIa. If the error of H(z) could be lowered to 3%, the same number of future measurements would be needed, but then the redshift coverage would only be required to reach z = 1. We also show that accurate measurements of the Hubble constant H 0 can be used as priors to increase the H(z) data's figure of merit.

Using the longitudinal expression of Hubble expansion rate for the general Lemaître-Tolman-Bondi (LTB) metric as a function of cosmic time, we examine the scale on which the Copernican principle holds in the context of a void model. By way of performing parameter estimation on the constrained Garcia-Bellido-Haugbolle void model, we show that the Hubble parameter data favors a void with a characteristic radius of 2-3 Gpc. This brings the void model closer, but not yet enough, to harmony with observational indications given by the background kinetic Sunyaev-Zel'dovich effect and the normalization of near-infrared galaxy luminosity function. However, the test of such void models may ultimately lie in the future detection of the discrepancy between longitudinal and transverse expansion rates, a touchstone of inhomogeneous models. With the proliferation of observational Hubble parameter data and future large-scale structure observation, a definitive test could be performed on the question of cosmic homogeneity. Particularly, the spherical LTB void models have been ruled out, but more general nonspherical inhomogeneities still need to be tested by observation. In this paper, we utilize a spherical void model to provide guidelines into how observational tests may be done with more general models in the future. [ABSTRACT FROM AUTHOR]