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When an Autonomous Underwater Vehicle(AUV) sails near the surface of the sea,it will inevitably be subjected to wave disturbance. The heave and pitch motion caused by wave disturbance not only affects the navigation attitude of the AUV,but also leads to an increase in sailing resistance. As such, its energy consumption is increased. In this paper,the six degrees of freedom model of AUVs is established and linearized in order to achieve the weighted optimization of the sailing attitude and the resistance of the AUVs. The drag force model of the AUV is derived using the theory of potential flow. The Q matrix and R matrix are determined in the controller based on research into the drag force model. The Linear Quadratic Regulator(LQR)controller of the AUV is designed using the drag force model as the performance index. The simulation results show that after adding the LQR controller,the effects of reducing heave motion and pitch motion are 46.64% and 77.62% respectively, and the increased resistance caused by the pitch motion is reduced to 1/6 of its original value. The results show that the multiple optimum of attitude and sailing resistance is realized,the energy consumption is decreased and the endurance of the AUV is increased.

A composite antibacterial film was prepared using agar and carrageenan as film-forming substrates, glycerol as the plasticizer, and different concentrations of the antibacterial agent nisin, and its physical and chemical indexes were comprehensively evaluated. This study was aimed at preventing microbial growth on blueberries and ameliorating the environmental pollution caused by traditional petroleum-based packaging materials. When the concentration of nisin in the compound antibacterial film was 0.28%, the antibacterial widths of Staphylococcus aureus and Listeria sp. were 3.326 and 1.812 mm, respectively; the water solubility, light transmittance, and tensile strength of the film were 45.01%, 79.78%, and 16.09 MPa, respectively. Therefore, the antibacterial film exhibited good water solubility and antibacterial, optical, barrier, and mechanical properties. Blueberries packaged with this antibacterial film at 4 and 20 ° had 4.20 and 2.46 lg cfu/g, respectively, of microbial content at the end of storage, and exhibited lower nutrient loss. Therefore, the composite film prepared for this test can help prolong the shelf life of blueberries. [ABSTRACT FROM AUTHOR]

To rapidly identify anaerobic ammonium-oxidizing (anammox) bacteria in environmental samples, a cloning-independent method based on Terminal Restriction Fragment Length Polymorphism (T - RFLP) was proposed. Based on SILVA (R108) SSU Ref database containing 400 16S rRNA gene sequences of anammox bacteria, defined lengths of terminal restriction fragments (T - RFs) were predicted by virtual PCR and restriction enzyme digestion using suitable PCR primers (Amx368f - Amx820r) and restriction enzyme (Mspl & Rsal). Then the genus of anammox bacteria was identified by comparative analysis of T - RFs. The repeatability and sensibility analysis results show that the anammox bacteria specific T - RFLP analysis is a reliable tool to rapidly assess the complexity of anammox bacteria in environmental samples. [ABSTRACT FROM AUTHOR]