Search

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]

The magnetic properties and structural phase transformations of Heusler alloys [Ni.sub.2+x][Mn.sub.1-x]Ga and [Ni.sub.2-x][Mn.sub.1+x/2][Ga.sub.1+x/2] were investigated. It was found that the martensitic transformation temperature increases and the Curie temperature decreases with decreasing Mn concentration in the [Ni.sub.2+x][Mn.sub.1-x]Ga system, but the magnetic properties decrease faster than those do in the [Ni.sub.2-x][Mn.sub.1+x/2][Ga.sub.1+x/2] system. It suggests that the influence of the conduction electron concentration and the distance between Mn atoms on the Curie temperature is stronger than the magnetic dilution effect. The martensitic transformation temperature shows a peak value at x = 0.06 in the [Ni.sub.2-x][Mn.sub.1+x/2][Ga.sub.1+x/2] system. A large stress-free magnetic-field-induced strain (MFIS) of 1.8% has been obtained at room temperature in a single crystal sample with the composition in the first system. Index Terms--Magnetic-field-induced strain, magnetic properties, phase transformation.

According to large daily temperature difference, strong solar radiation and significant change of air humidity in the alpine area of Tibet, a field experiment was conducted to analyze the oat's diurnal variation of the leaf water potential (ψL), transpiration rate (Tr) and net photosynthetic rate (Pn). Meanwhile, the relationship between oat's physiological indicators and typical meteorological factors (atmospheric temperature (T), solar radiation (Rs), relative air humidity (RH)) were investigated with regression models. Results showed that the oat's daily change curve of ψL showed 'V-type' in the seeding and heading stages and 'W-type' in the jointing and tillering stages. As shown in the results, oat's Pn presented a decreasing tendency in a day and the peak appearing between 9:00 and 10:00 at one day in each growing stage. The Tr presented double-peak curves and midday depression in the seeding and heading stages. The variation tendency about oat's Tr in the tillering stage and jointing stage was "Multipeak" type without distinct midday depression and parabolic tendency. By multiple regression analysis between the data of oat's physiological indexes and comprehensive factors, the ψL, Tr and Pn of oat in alpine region can be predicted under condition of adequate water supply. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Granulocyte colony-stimulating factor (G-CSF) plays a role in regulating phosphatidylinositol-3-kinase/serine/threonine kinase (PI3K/AKT) pathway, affecting cell proliferation and apoptosis, and inducing vascular endothelial growth factor (VEGF) expression. This study investigated the mechanism of G-CSF on angiogenesis and neural protection after intracerebral hemorrhage (ICH). MATERIALS AND METHODS: The rats were divided into four groups, including sham, ICH, ICH+G-CSF, and ICH+G-CSF+LY294002 (PI3K/AKT signaling pathway specific inhibitor). Cerebral neurological dysfunction was tested by Garcia scoring. Cell apoptosis was detected by transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) assay. Angiogenesis marker CD34 expression, PI3K/AKT signaling pathway, B-cell lymphoma-2 (Bcl-2), and VEGF expressions were compared by IHC. Rat cerebral nerve RN-c cells were divided into four groups, including control, oxygen-glucose deprivation (OGD), OGD+G-CSF, and OGD+G-CSF+LY294002. RESULTS: Neurological dysfunction was more evident; CD34+ cell number, VEGF expression, and cell apoptosis significantly increased; phosphorylated AKT (p-AKT) and Bcl-2 levels markedly reduced in ICH group compared with sham group. G-CSF apparently up-regulated p-AKT and Bcl-2 expressions, attenuated cell apoptosis, and elevated CD34+ cell number. LY294002 significantly decreased p-AKT, Bcl-2, and VEGF expressions, and alleviated the cell apoptosis protective and angiogenesis effect induced by G-CSF. OGD treatment induced RN-c cell apoptosis, down-regulated p-AKT and Bcl-2 expressions, and enhanced the tube capacity of vascular endothelial cells (VEC). G-CSF markedly elevated p-AKT and Bcl-2 contents in RN-c cells, declined cell apoptosis, increased p-AKT and VEGF levels in VEC, and enhanced tube capacity. CONCLUSIONS: G-CSF enhanced PI3K/AKT signaling pathway activity, promoted Bcl-2 and VEGF expression, reduced nerve cell apoptosis, and enhanced tube capacity of VECs, which may be the mechanism of G-CSF in improving neurological function and angiogenesis after ICH. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To study the structural and functional changes in mitochondria in astrocytes of the cerebral cortex of the rats in the simulated sepsis environment in vitro and the relationship between these changes and the biogenesis of mitochondria in astrocytes by establishing models of sepsis astrocytes. MATERIALS AND METHODS: The structural and functional changes in mitochondria in astrocytes of the cerebral cortex of the rats were evaluated. The ultra structural changes in the mitochondria, astrocytes, and ultrathin sections, were observed with a transmission electron microscope. The expression of the regulatory factors related to biogenesis of mitochondria in astrocytes of the cerebral cortex of the rats was evaluated in various experimental groups. RTPCR and Western blot were used to evaluate the expression of the regulatory factors related to biogenesis of mitochondria in astrocytes of the cerebral cortex of the rats. The "point grid method" was used to evaluate the volume density of the mitochondria in the astrocytes of the cerebral cortex of the rats in various experimental groups. The Western blotting was used to evaluate the role of fusion and fission of mitochondria in the astrocytes of the cerebral cortex of the rats in various experimental groups in regulating the expression of the protein-OPAI and DRPI. RESULTS: In the sepsis astrocyte models established by co-incubation of LPS and IFN-γ and astrocytes of the cerebral cortex of the rats, the mitochondria with a minor injury in the 6 h group (2.97± 0.92) increased significantly when compared with those in the 0 h group (1.08±0.95), 12 h group (1.70±1.01), and 24 h group (1.59±0.55) (p<0.05); the concentration of adenosine triphosphate (ATP) in the astrocytes of the cerebral cortex of the rats in the 6 h, 12 h, and 24 h groups increased significantly when compared with that in the 0 h group (p<0.05). PGC-1α mRNA, NRF-1 mRNA, NRF-2α mRNA, NRF-2β mRNA, and mitochondrial transcription factor A (TFAM) mRNA in the astrocytes of the cerebral cortex of the rats in the 6 h and 12 h groups increased significantly when compared with those in the 0 h group (p<0.05); the concentration of TFAM mRNA (1.20±0.19) increased significantly when compared with that in the 0 h group (p<0.05). The OPAI protein concentration (1.21±0.17:1.34±0.06) and DRPI protein concentration (1.04±0.05; 1.05±0.05) in the astrocytes of the cerebral cortex of the rats in the 12 h group (1.25±0.17), 24 h group (1.33±0.24), and 6 h group increased significantly when compared with that in the 0 h group (p <0.05). CONCLUSIONS: The experimental sepsis conditions can cause a minor injury of the ultrastructure of the mitochondria in the astrocytes of the cerebral cortex of the rats. The biogenesis of the mitochondria in the astrocytes of the cerebral cortex of the rats was strengthened to cater for the increased demand for energy of the astrocytes under the sepsis conditions and finally recover the ultrastructure of the mitochondria with a minor injury. In response to the increased mitochondrial biogenesis, the activities of the mitochondrial fusion and fission of the astrocytes of the cerebral cortex of the rats were increased. [ABSTRACT FROM AUTHOR]

The effect of Cux substituted for Gax on the thermodynamic characteristic, evolution of phases and fracture behavior in Ni50Mn30Ga20 − xCux alloys have been investigated. The results show that the martensitic transformation, reverse transformation temperatures and average interface temperature of Ni50Mn30Ga20 − xCux sample increase remarkably with increased content of Cu. The hysteresis temperature of the austenite to martensite transition firstly showed a steep rising trend, then almost reduced to a lower rate with the increased content of Cu up to 4 at.% (the maximum level of copper addition studied). The (202) diffraction peak position was observed to shifted towards high angles, when the Cu content was lower than 1 at.%. Further, the, M202 diffraction peak was found to split into two diffraction peaks when the Cu content was more than 1 at.%. In addition, the compressive strength and fracture strain of alloys is clearly enhanced with increased content of Cu. Furthermore, the fracture type of Ni50Mn30Ga20 − xCux alloys was found to changes from intergranular fracture for the Ni–Mn–Ga alloys, to transgranular cleavage fracture with increase in Cu content. [ABSTRACT FROM AUTHOR]

What is known and objectives Choosing an alternative statin is recommended when managing statin-associated muscle symptoms ( SAMS) and new hydrophilic statins are often suggested. We report on a case of statin-associated muscle damage that was successfully managed by simplifying the patient's combination therapy with simvastatin-ezetimibe to simvastatin alone. Case summary The patient experienced SAMS when he was successively treated with atorvastatin, rosuvastatin, Xuezhikang capsule and combined simvastatin/ezetimibe therapy. However, the patient tolerated simvastatin therapy well even at a dose of 40 mg/day. What is new and conclusion Our case suggests that patients with SAMS who are intolerant to a wide variety of statins may be successfully managed with simvastatin monotherapy. [ABSTRACT FROM AUTHOR]

The effects of aging on martensitic transformation and microhardness were investigated for Ni53Mn23·5Ga18·5Ti5 ferromagnetic shape memory alloy. The results show that precipitation has obvious effect on martensitic transformation temperature and the microhardness increases with increasing aging temperature up to 973 K, and then decreases gradually with the further increase in aging temperature. [ABSTRACT FROM AUTHOR]

How to alleviate the damages of cascading failures triggered by the overload of edges/nodes is common in complex networks. To describe the whole cascading failures process from edges overloading to nodes malfunctioning and the dynamic spanning clustering with the evolvement of traffic flow, we propose a capacity assignment model by introducing an equilibrium assignment rule of flow in artificially created scale-free traffic networks. Additionally, the capacity update rule of node is given in this paper. We show that a single failed edge may undergo the cascading failures of nodes, and a small failure has the potential to trigger a global cascade. It is suggested that enhancing the capacity of node is particularly important for the design of any complex network to defense the cascading failures. Meanwhile, it has very important theoretical significance and practical application worthiness in the development of effective methods to alleviate the damage of one or some failed edges/nodes. [ABSTRACT FROM AUTHOR]

In the case of two-way traffic, there are two opposite-direction flows on every road and serious unsymmetrical flows exist in rush-hour periods. One of the primary methods used for handling this kind of traffic flow is the use of reversible lanes. Which and how many lanes should be adjusted are optimization problems. They can be treated as a network design problem, i.e. the optimal decision on the resource distribution of a street and highway system in response to a growing travel demand. This article studies a new form of transportation network design problem by performing the strategy of reversible lanes. In order to describe this problem, a bi-level programming model is given in which the upper level model is to make the total system cost and flow entropy minimum, while the lower level is a stochastic user equilibrium assignment with an advanced traveller information system. Finally, the numerical example shows that, by adopting the reversible lane and advanced traveller information system, the total system cost will be greatly reduced. [ABSTRACT FROM AUTHOR]

In order to solve the problems of the 2.45 GHz magnetron used in asphalt pavement maintenance as the longer heating time and high energy consumption when heating unit area, the paper brings forward the 5.8 GHz magnetron using in asphalt pavement maintenance. CST and ANSYS simulation software were first used to study the temperature rise and depth of heating asphalt pavement using 2.45 GHz and 5.8 GHz magnetron. Then the experimental verification was carried through. The 5.8 GHz magnetron can be used effectively in asphalt pavement maintenance. The research results show that: the temperature rising rate of the 5.8 GHz magnetron heating asphalt pavement is 2–3 times of 2.45 GHz magnetron in the distance within 0–75 mm of the asphalt concrete pavement. Heating 8–10 minutes, temperature rise within 0–75 mm of asphalt pavement can meet the asphalt road surface maintenance. The heating asphalt pavement depth of 5.8 GHz magnetron which is about 7 cm–8 cm is half of the 2.45 GHz magnetron. Heating the same area of asphalt pavement to the same temperature, the input power of 5.8 GHz magnetron maintenance equipment is 1/3 of the 2.45 GHz magnetron maintenance equipment. [ABSTRACT FROM AUTHOR]

Different from conventional metal foams, sintered metallic hollow sphere (MHS) material contains a certain volume fraction of enclosed pore space inside the spheres, as well as the interstitial porosity between the sintered neighbors, and this mixed open/closed-cell characteristic offers low density, high stiffness, and good energy absorption capacity. It is a new type of prospective light weight material for automotive and aerospace industry. In this study, the mechanical properties, especially the dynamic behaviors of the MHS materials are examined experimentally. Basic geometrical measurements reveal that the two types of MHS specimens we used were composed of randomly packed hollow spheres with uniform outer radius (0.9 and 1.5 mm) and wall thickness 0.05 mm (relative density <6%). A very long, plateau length (up to 67% nominal strain) with almost constant stress was found in quasi-static tests, indicating that they are appropriate for energy absorption applications. Dynamic tests were performed by using a modified split Hopkinson pressure bar (SHPB), and significant dynamic strength enhancements were observed. Moreover, based on the experimental observations the relevant collapse and dynamic enhancement mechanisms are discussed, whereas the localization phenomena in dynamic crushing process were revealed by using the particle image velocimetry correlation method. [ABSTRACT FROM AUTHOR]

The paper puts forward microwave deicing after analyzing the shortage of deicing using chemistry, thermal and mechanism. It points out that study of microwave deicing is restricted by deicing efficiency. In order to improve the microwave deicing efficiency and achieve fast deicing in winter road maintenance, the influence factors of microwave deicing efficiency are studied. Then frequency of microwave is simulated by CST software. The findings indicated that deicing efficiency is concerned with the microwave frequency, electric field intensity of microwave, road material, environmental temperature, thickness of ice, impurity content of ice, heating mode of microwave, distance between road and waveguide mouth and so on. At the same condition, the deicing efficiency of 5.8 GHz magnetron is four times more than 2.45 GHz magnetron. [ABSTRACT FROM AUTHOR]

The article focuses on a study which examined the mechanical properties and shape-memory behaviors of poly(L-actide-co-e-caprolactone) (PCLA) copolymers. It notes that a variety of chemical compositions were used to synthesize a series of biodegradable PCLA copolymers. Results of the study showed that the copolymer compositions influenced the mechanical properties significantly. It also found a decline in the tensile strength of copolymers due to an increase in e-caprolactone content.

The thermal properties, crystalline structure and shape memory effects of poly( l-lactide) (PLLA) and poly( l-lactide-co-ε-caprolactone) (PCLA) copolymers are systematically investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and tensile tests. The effects of the deformation strain on the shape recovery rate and recovery stress are also revealed. The polymers have the PLLA crystal and the amorphous phase, which are served as the fixed phase and reversible phase, respectively. The shape recovery rate and the recovery stress are significantly affected by the compositions and the deformation strain. With the increase of the deformation strain, the shape recovery rate decrease and higher shape recovery rate can be obtained in the polymers which have higher ε-CL content. However, the variation of recovery stress with the deformation strain is quite different and the maximum recovery stress of all polymers exceeds 3 MPa. [ABSTRACT FROM AUTHOR]