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The measurement method and quantitative indexes of iron ore consolidation characteristic temperature (CCT) during roasting, including consolidation starting temperature, highest consolidation rate temperature, and consolidation termination temperature, were improved based on previous research. The mineral properties of V–Ti magnetite (Panzhihua) were analyzed, and the CCT of V–Ti magnetite was calculated. To investigate the effect of mineral types on CCT, a series of trials were carried out by using various ores, including high-grade magnetite ore, high silicon iron ore, and V–Ti magnetite ore. The greatest shrinkage of V–Ti magnetite was 6.7%, the consolidation starting temperature was 991 °C, and the termination temperature was 1384 °C. The results of X-ray diffraction analysis indicated that the V–Ti magnetite ore was composed of titanomagnetite, peridotite, and other minerals, which is more complicated than conventional magnetite. As a result, the temperature at the maximum rate of consolidation and the temperature at the termination of consolidation are the greatest. FeTiO3and MgFe2O4in V–Ti magnetite may inhibit the creation of sinter necks between hematite particles. Liquid phase occurs inside the pellet when the temperature surpasses 1250 °C, which may accelerate particle growth and the formation of a sintering neck within the pellets.

Methods of experimental observations, theoretical analysis and meso-scale modeling were used to study the propagation processes of shock waves in dry and wet sandstone under dynamic impact in this paper. According to the results from the dynamic impact experiments with velocity of 0.2–0.5 km/s, it was found that the velocity of shock wave increases linearly with water content. Additionally, the velocity of the shock wave in the sandstone showed a linearly increased regularity with the increasement of the impact velocity, which was proved by theory in this paper. Furthermore, meso-scale simulation models were performed and the simulation results showed that sandstone's porosity reduced the shock waves velocity compared to nonporous materials. Pore space filled with water counteracts the effects of porosity, resulted in larger shock wave velocity.

We propose an experimental scheme to simulate the dynamical quantum Hall effect and the related interactioninduced topological transition with a superconducting-qubit array. We show that a one-dimensional Heisenberg model with tunable parameters can be realized in an array of superconducting qubits. The quantized plateau, which is a feature of the dynamical quantum Hall effect, will emerge in the Berry curvature of the superconducting qubits as a function of the coupling strength between nearest-neighbor qubits. We numerically calculate the Berry curvatures of two-, four-, and six-qubit arrays and find that the interaction-induced topological transition can be easily observed with the simplest two-qubit array. Furthermore, we analyze some practical conditions in typical experiments for observing this dynamical quantum Hall effect. [ABSTRACT FROM AUTHOR]

Hydroxyapatite coatings with biological activity on magnesium alloy can effectively reduce its degradation rate in the physiological environment. Pre-calcification was applied as the pretreatment in this paper. And then, hydroxyapatite coatings were deposited on the surface of the magnesium alloy in non-magnetic field, near the antarctic and the arctic of a constant magnetic field respectively. The morphology, phase composition and crystal structure of the coatings were analyzed using SEM and XRD. The results show that the crystals of the coatings affected by the magnetic fields are preferential orientation significantly.

Microstructure evolution characteristics and the influence of the intial grain size on the dynamic recrystallization of AZ31 were investigated by rolling at deformation temperature of 280 °C, 30% reduction and strain rate of 5.6s-1. The results indicate that under the present deformation condition, when the grain size is 6.2μm the dynamic recrystallization does not occur , twinning dynamic recrystallization (TDRX) occurs when the original grain size are of 7.9μm and 12.7μm, when the original grain size is 21.1μm rotating dynamic recrystallization (RDRX) occurs.

Soil particle transport causes serious environmental problems, and particle interaction forces will be the controlling force for soil transport during rainfall. However, few reports can be found in literature concerning the quantitative evaluation of particle interaction forces on soil particle transport. In this study, purple soil was adopted to study soil particle transport under different force strength conditions of particle interaction during rainfall simulation with precipitation intensity of 150 mm h–1for 110 min. We first analyzed soil particle interaction forces quantitatively under different KNO3and Ca(NO3)2concentrations (0.0001, 0.001, 0.005, 0.01, 0.05, 0.1, and 1 mol L–1) which adjusted surface potential of soil particle from –323 to –50 mV. The results indicated that the net Derjaguin–Landau–Verwey–Overbeek (DLVO) force could not solely cause soil particle transport during rainfall. The hydration repulsive force, which was much stronger than the DLVO force, played a crucial role in soil particle transport. During rainfall, soil particle in aggregate was separated to a distance of 1.5 to 2 nm by the strong hydration repulsive force (swelling process). Then aggregate was thoroughly broken by the electrostatic repulsive force. The hydration repulsive force dominated aggregate swelling, and the electrostatic force determined the transport intensity. We found that, at surface potentials lower than –100 mV, soil transport did not occur even precipitation intensity reaching 150 mm h–1; and –200 mV of surface potential was the critical potential for soil particle transport. We conclude that the surface hydration force and electrostatic repulsive force were the controlling force for soil particle transport during rainfall.

Rapid deposition of hydroxyapatite on Mg-alloy in concentrated simulated body fluid (5×SBF) and modified simulated body fluid (m-SBF) was investigated. By biomineralization method, hydroxyapatite coating was deposited on Mg-alloy with pre-calcification treatment. Scanning electron microscope (SEM), energy disperse spectroscopy (EDS) and X-ray diffraction instrument (XRD) were applied to analyze the deposition product of biomineralization and the related mechanism. The results showed that pre-calcification treatment on Mg-alloy can lead to a quite rapid deposition of hydroxyapatite. Ionic concentrations in SBF solutions affected the structure of hydroxyapatite greatly. A homogeneous plate-like apatite coating was induced on Mg alloy sample in m-SBF solution which is promising for the future practice.

It has been recently demonstrated that a singlet-triplet spin qubit in semiconductor double quantum dots can be controlled by changing the height of the potential barrier between the two dots ("barrier control"), which has led to a considerable reduction of charge noises as compared with the traditional tilt control method. In this paper we show, through a molecular-orbital-theoretic calculation of double quantum dots influenced by a charged impurity, that the relative charge noise for a system under the barrier control not only is smaller than that for the tilt control but actually decreases as a function of an increasing exchange interaction. This is understood as a combined consequence of the greatly suppressed detuning noise when the two dots are symmetrically operated, as well as an enhancement of the interdot hopping energy of an electron when the barrier is lowered which in turn reduces the relative charge noise at large exchange interaction values. We have also studied the response of the qubit to charged impurities at different locations and found that the improvement of barrier control is least for impurities equidistant from the two dots due to the small detuning noise they cause but is otherwise significant along other directions. [ABSTRACT FROM AUTHOR]

We present a theoretical study of a four-electron four-quantum-dot system based on molecular-orbital methods, which hosts a pair of singlet-triplet spin qubits. We took into account the admixture of electron wave functions in all dots, and we found that this mixing of wave functions has consequences to the energy spectrum, exchange interaction, and gate crosstalk of the system. Specifically, we found that when the two singlet-triplet qubits are close enough, some of the states are no longer dominated by the computational basis states, and the exchange interaction cannot simply be understood as the energy difference between the singlet and triplet states. Using the Hund-Mulliken calculation of the Hubbard parameters, we characterized the effective exchange interaction of the system, and we found good agreement with results calculated by taking energy differences where applicable. We studied the two commonly conceived schemes coupling two qubits, namely the exchange and capacitive coupling, and we found that when the interqubit distance is at certain intermediate values, the two kinds of coupling are comparable in strength, complicating the analyses of the evolution of the two qubits. We also investigated the gate crosstalk in the system due to the quantum-mechanical mixing of electron states, and we found that while this effect is typically very weak, it should not be ignored if the spacing between the qubits is similar to or less than the distance between the double dots that constitute the qubit. [ABSTRACT FROM AUTHOR]

We study theoretically the responses of the dynamically corrected gates to time-dependent noises in the exchange-only spin-qubit system. We consider 1/f noises having spectra proportional to 1/ωα, where the exponent α indicates the strength of correlation within the noise. The quantum gate errors due to noises are extracted from a numerical simulation of randomized benchmarking and are compared between the application of uncorrected operations and that of dynamically corrected gates robust against the hyperfine noise. We have found that for α≳1.5, the dynamically corrected gates offer a considerable reduction in the gate error and such a reduction is approximately two orders of magnitude for the experimentally relevant noise exponent. On the other hand, no improvement of the gate fidelity is provided for α≲1.5. This critical value of αc≈1.5 is larger than that for the cases for the singlet-triplet qubits. The filter transfer functions corresponding to the dynamically corrected gates are also computed and compared to those derived from uncorrected pulses. Our results suggest that the dynamically corrected gates are useful measures to suppress the hyperfine noise when operating the exchange-only qubits. [ABSTRACT FROM AUTHOR]