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Underwater vehicles are key carriers for underwater inspection and operation tasks, and the successful implementation of these tasks depends on the positioning and navigation equipment with corresponding accuracy. In practice, multiple positioning and navigation devices are often combined to integrate the advantages of each equipment. Currently, the most common method for integrated navigation is combination of the Strapdown Inertial Navigation System (SINS) and Doppler Velocity Log (DVL). Various errors will occur when SINS and DVL are combined together, such as installation declination. In addition, DVL itself also has errors in the measurement of speed. These errors will affect the final accuracy of the combined positioning and navigation system. Therefore, error correction technology has great significance for underwater inspection and operation tasks. This paper takes the SINS/DVL integrated positioning and navigation system as the research object and deeply studies the DVL error correction technology in the integrated system.

The purpose of this study was to investigate the anti-Newcastle disease virus (NDV) activities of baicalin from Scutellaria baicalensis, a Traditional Chinese Medicine in vitro. Chicken embryo fibroblasts (CEFs) were infected with NDV, and quantitative analysis of apoptotic cells was performed using flow cytometry. Cytotoxicity and anti-viral activities of baicalin were studied using the MTT method. The results showed that the maximal safe concentrations of baicalin to CEFs was 1 × 2(-2) mg/ml. Baicalin could directly kill NDV, inhibit the infectivity of NDV to CEF and block intracellular NDV. It inhibited the apoptosis of NDV-infected CEFs and suppressed the spread of NDV. These results indicate that baicalin has strong anti-NDV activity and has the potential for use as components of an antiviral drug.

Mg-5Li-1Al-0.5Y alloy was rolled with different directions. The microstructure, mechanical properties and texture of the specimens were investigated with optical microscope, tensile tester and X-ray diffraction. The results show that changing rolling directions can refine the grain size of as-rolled alloys. Meanwhile, rolling directions have an obvious influence on the mechanical properties and texture of Mg-5Li-1Al-0.5Y alloy, thus affecting the anisotropy of the alloy. The sheet, of which the RD (rolling direction) and ND (normal direction) are both changed between two passes, possesses the smallest anisotropy. From the texture results, changing rolling directions reduces the maximum pole density, making the highest point distribution region excursion and the highest point distributes more scatteredly.

Mg–5Li–1Al (LA51) and Mg–5Li–1Al–0.5Y (LA51–0.5Y) alloys were smelted and rolled with different accumulated strains (36% and 68%) and rolling temperatures (373 K and 573 K). The microstructure, mechanical properties, fracture morphology and texture of the specimens were investigated. Results show that, due to the PSN (particle stimulate nucleation) mechanism, the addition of 0.5 wt.% Y improves the deformation resistance and weakens the basal texture of LA51 alloy. The effect of Y on UTS (ultimate tensile strength) of as-rolled alloys is more obvious than that of the as-cast alloy. Accumulated strain and rolling temperature could influence the twinning number, slip systems and DRX (dynamic recrystallization), thus affecting the microstructure and mechanical properties of the alloy. Under the proper combination of the above factors, the as-rolled LA51–0.5Y alloy with an accumulated strain of 68% at 573 K possesses the best comprehensive mechanical properties. Keywords: Mg–Li alloy, Accumulated strain, Rolling temperature, Microstructure, Mechanical property, Texture

This paper investigates the microstructure and texture evolution of as-rolled Mg-5Li-3Al-2Zn-1.2Y-0.8Nd. During rolling (both warm rolling and hot rolling), many twins appear in the alloy, some of which are cross-twins. Dynamic recrystallization occurs, resulting in grain refinement. With the increase of rolling reduction percentage, basal texture appears, and then finally non-basal texture appears. The non-basal texture during warm rolling begins to appear under a smaller rolling reduction percentage than that during hot rolling. When the rolling reduction is 28 %, the angles between the majority of c-axes and rolling direction are mainly about 25°. When the rolling reduction percentage is 52 %, the textures are strengthened.

Y and Nd are simultaneously added into Mg–5Li–3Al–2Zn alloy. It is found that there exist the phases of α-Mg, AlLi, Al11Nd3 and Al2Y in the alloys. When the contents of Y and Nd are 1.2% and 0.8%, respectively, the grain is the finest with an average size of 30 μm, and the tensile strength of the alloy reaches 231 MPa, the elongation reaches 16%. When the ratio of Y to Nd is 1.2:0.8, there is a synergistic strengthening effect.

Mg–5Li–1Al–0.5Nd/0.5Y alloys were prepared using a vacuum induction melting furnace. The microstructure and phase composition were investigated by optical microscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy and X-ray diffraction. The mechanical properties of alloys were measured with tensile tester. The addition of rare earth element results in the formation of an Al–RE compound, such as Al2Nd and Al2Y, and it has a refining effect on the microstructure of the alloy. Dynamic recrystallization that happens during the rolling refines the grains of the alloy obviously. The addition of rare earth element activates the non-basal slip system, changes stacking fault energy of magnesium alloy, and weakens the basal texture because of PSN (particle stimulated nucleation) mechanism. The addition of Nd/Y enhances the strength anisotropy of the alloy, while it weakens the elongation anisotropy of the alloy.

The microstructure and mechanical properties of Mg–(6, 9)RY–4Zn alloys (RY: Y-rich misch metal) prepared by extrusion and aging treatment have been investigated. The results demonstrate that the alloys in the as-extruded state and peak-aged state share some similar characteristics, i.e. strip-like 14H long period stacking ordered (LPSO) phase and fine dynamic recrystallization (DRX) grains with 14H LPSO lamellae, while additional basal plane stacking faults (SFs) are formed in the DRX grains of the peak-aged alloys. The peak-aged Mg–9RY–4Zn alloy exhibits optimal comprehensive mechanical properties: the microhardness is 109 Hv at room temperature (RT); the ultimate tensile strength ( σ ), yield strength ( σ 0.2 ) and elongation ( e ) are 285 MPa, 376 MPa, 8.6% at RT and 243 MPa, 316 MPa, 16.3% at 250 °C, respectively. The high mechanical properties are mainly attributed to the fine grains, thermal stable LPSO phase and profuse SFs.

The purpose of this study was to investigate the anti-Newcastle disease virus (NDV) activities of baicalin from Scutellaria baicalensis, a Traditional Chinese Medicine in vitro. Chicken embryo fibroblasts (CEFs) were infected with NDV, and quantitative analysis of apoptotic cells was performed using flow cytometry. Cytotoxicity and anti-viral activities of baicalin were studied using the MTT method. The results showed that the maximal safe concentrations of baicalin to CEFs was 1 × 2(-2) mg/ml. Baicalin could directly kill NDV, inhibit the infectivity of NDV to CEF and block intracellular NDV. It inhibited the apoptosis of NDV-infected CEFs and suppressed the spread of NDV. These results indicate that baicalin has strong anti-NDV activity and has the potential for use as components of an antiviral drug.

In order to deliver the maximum available power to the load under the condition of varying solar irradiation and environment temperature, maximum power point tracking (MPPT) technologies have been used widely in PV systems. Among all the MPPT schemes, the chaos method is one of the hot topics in recent years. In this paper, a novel two-stage chaos optimization method is presented which can make search faster and more effective. In the process of proposed chaos search, the improved logistic mapping with the better ergodic is used as the first carrier process. After finding the current optimal solution in a certain guarantee, the power function carrier as the secondary carrier process is used to reduce the search space of optimized variables and eventually find the maximum power point. Comparing with the traditional chaos search method, the proposed method can track the change quickly and accurately and also has better optimization results. The proposed method provides a new efficient way to track the maximum power point of PV array.

Due to the super light-weight property,Mg-Li alloys are very promising in the fields of aerospace and military defense.Up to now,many studies about hot deformation behavior of Mg-Li alloys have been reported.However,there are little researches on their room-temperature deformation behavior.Therefore,the plastic deformation mechanism of Mg-Li alloys needs further investigated.It is known that addition of RE to Mg alloys could cause solid solution strengthening, fine grain strengthening and secondary phase strengthening.Nevertheless,reports refer to the effect of RE on the texture of Mg-Li alloys.This work was devoted to study the microstructure,mechanical properties and the evolution of texture after compression at room-temperature of the as-cast Mg-5Li-3Al-2Zn and Mg-5Li-3Al-2Zn-1.2Y-0.8Nd alloys with OM,SEM,XRD,ODF and EBSD techniques as well as material testing machine.The results show that with the addition of Y and Nd,most of the filamentous AlLi intermetallic compounds are suppressed and substituted by other two intermetallics Al_2Y and Al_(11)Nd_3.Meanwhile,the grains are refined with the average size of 30μm.ODF analysis indicates that for Mg-5Li-3Al-2Zn alloy,when the strain is 0.17 the C-axis of most grains is roughly 75°form ND,while in Mg-5Li-3Al-2Zn-1.2Y-0.8Nd,when the strain is 0.10 the strong prismatic texture appeares,which means that the(1010) of most grains parallel to ND. Both of the two alloys exhibit high plasticity when tested at room-temperature,while the compression deformation of the alloy containing Y and Nd can reach up to 27%.The combined addition of Y and Nd significantly reduces the c/a of the magnesium lattice,weakes basal texture,activates the pyramidal slip system and,especially,activates the prismatic slip system which seldom occurs at room-temperature in magnesium alloys.