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The prediction of basin water quality has become an urgent need for water environment management, where water pollution is on the increase. Currently, physical models are primarily used for water quality predictions, but the models are not adaptable for the automatic future prediction of watershed water quality owing to their non-automatic boundary setting. The development of big data, which has led to artificial intelligence (AI) technology, has remedied the deficiency of physical models and has been widely used in water quality prediction. However, the accuracy of AI models depends only on the quantity and quality of dataset, which is applied on specific and discrete sections with enough data and difficult to extend to regions with limited monitoring data. Thus, we constructed migration and distribution gates to express the spatial influence of different variables from different sections on the water quality of a specific and discrete section. The temporal processes were expressed by degradation equation. The migration gate, distribution gate and degradation equations were incorporated into Long Short-Term Memory Network (LSTM) to improve the operation mechanism of the LSTM algorithm to create the Im-LSTM model, which considers both the temporal influence of a specific section and the spatial influence of other sections on a specific section at basin scale. Compared to ANN, LSTM, Im-LSTM showed the best performance for basin water quality prediction, especially for mainstream sections at sudden pollution process. Thus, the proposed Im-LSTM provides a new approach for water environment supervision. [ABSTRACT FROM AUTHOR]

The effects of different forming process on the microstructure, martensitic transformation, and mechanical properties of the Ni50Mn34In14Co2 (numbers indicate at.%) alloys were investigated in detail. The results show that the microstructure of Ni50Mn34In14Co2 alloy consists of the matrix and the second phase by powder hot forging technology under the forces in different directions and spark plasma sintering (SPS), and the prepared sample has obvious preferred orientation by applied force in the three directions. The grain and the second phase of prepared sample were obviously refined by the hot forging technology. The martensitic transformation behavior was almost unchanged by different forming process. In addition, the shape memory effect of prepared Ni50Mn34In14Co2 alloy was significantly enhanced by different forming processes. [ABSTRACT FROM AUTHOR]

Effects of aggregate size and shape on monotonic shear behaviour of unreinforced and geogrid-reinforced aggregate interfaces were systematically investigated through direct shear tests. Five different grades of angular aggregates and five kinds of rounded aggregates with identical particle size distribution were selected as test materials. Experiment results revealed the coupling effects of particle shape and aperture ratio (AS/D50), defined as the ratio of geogrid aperture size (AS) to the average particle size of aggregate (D50), on the shear behaviour of the unreinforced and reinforced interfaces. The peak shear stress, shear displacements corresponding to peak shear stress and residual shear stress, as well as maximum dilation of aggregate–geogrid interfaces at each AS/D50 were greater than those of glass beads–geogrid interfaces. The largest interface shear strength coefficient of aggregate–geogrid interfaces was achieved at AS/D50 = 2.55, and the optimum reinforcement of glass beads–geogrid interfaces appeared at AS/D50 = 5.05. The shear strength decreased more after the peak when the value of AS/D50 was relatively small, and the post-peak strength reduction of aggregate–geogrid interfaces was more pronounced. A generalised stress-dilatancy relationship was proposed, which introduced a variable dilatancy index (ζ) that reflected the effects of aperture ratio and particle shape. [ABSTRACT FROM AUTHOR]

Reinforced soil structures are often subjected to both static and dynamic loads. However, experimental data concerning the interaction of soil–geosynthetic interfaces under normal dynamic loads are scarce. This paper reports on a series of large-scale direct shear tests that are used to investigate the shear behaviour of a gravelly soil–geogrid interface under normal cyclic load (NCL) conditions. The results show that the shear stress magnitude under NCL conditions is generally between the shear stresses under normal static load (NSL) conditions corresponding to the upper and lower bounds of the NCL. The upper and lower envelopes of the shear stress–displacement curve increase with increasing initial stress and amplitude. The enhancement coefficient ( α) is used to describe the degree of influence of the additional cyclic load on the shear stress of the interfaces. The relative time shift between the shear stress ratio ( R NCL ) and the normal stress ( σ n ) is nearly a constant of 0.5 cycles, and the influence of the initial stress on the stress ratio is opposite to that of the amplitude. Finally, the volume change response is discussed under different normal load conditions. [ABSTRACT FROM AUTHOR]

With the growing trend of higher running speed and lighter body weight in the high-speed train, the influences of fluctuating crosswind on running stability and safety are becoming more and more not negligible, especially under the combined action of unsteady aerodynamic loads and random orbital excitation. In order to investigate this problem, a vehicle dynamic model of with 42 degree of freedom is built, in which the major body, two bogies and eight wheels are involved. The unsteady aerodynamic loads under stochastically fluctuating crosswind are obtained based on Cooper theory and the harmonic superposition method, and the random excitation of the track is also taken into consideration. For the vertical vibration originated from the fluctuating crosswind and the random track spectrum, the skyhook damping and the magneto-rheological fuzzy semi-active control strategies are individually applied to suppress the vibrating amplitude and improve the running stability. It is indicated that the vertical vibration under the coupling influence of the unsteady aerodynamic loads and the random orbital excitation are significantly increased, and the vibrating amplitude can be effectively suppressed by both the two different control approaches. It is also shown that the index of running stability in the case of the fuzzy control is evidently better than the skyhook damping. [ABSTRACT FROM AUTHOR]

Morphology and microstructure of dislocation etch pits in GaN epilayers etched by molten KOH have been investigated by atomic force microscopy, scanning electron microscopy, and transmission electron microscopy (TEM). Three types of etch pits (α, β, and γ) are observed. The α type etch pit shows an inversed trapezoidal shape, the β one has a triangular shape, and the γ type one has a combination of triangular and trapezoidal shapes. TEM observation shows that α, β, and γ types etch pits originate from screw, edge, and mixed-type threading dislocations (TDs), respectively. For the screw-type TD, it is easily etched along the steps that the dislocation terminates, and consequently, a small Ga-polar plane is formed to prevent further vertical etching. For the edge-type TD, it is easily etched along the dislocation line. Since the mixed-type TDs have both screw and edge components, the γ type etch pit has a combination of α and β type shapes. It is also found that the chemical stabilization of Ga-polar surface plays an important role in the formation of various types of dislocation etch pits. [ABSTRACT FROM AUTHOR]