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An interceptor is an appendage widely used for high-speed planing boats to reduce resistance and modify hull attitude by the lift force-induced, but the relationship between the induced lift force and the factors affecting it are still not clear, especially for the vessels other than the planing hull. In this paper, a model test of a series of models is performed to investigate the lift force induced by an interceptor and the influence of the affecting factors systematically. The lift forces induced by the interceptor are tested in the conditions of different velocities, interceptor heights, angles, and drafts in the towing tank. The effects of each factor and the coupled effects are analyzed. It is found by the experimental results that the lift coefficient of the induce lift force in the present investigation is approximately proportional to the square of the non-dimensional velocity and interceptor height, but the effect of the interceptor height is of a limited extent. The influence of angle and draft on the lift force induced by the interceptor cannot be ignored in the present study. The induced lift force is decreased when the angle of the plate is reduced and is enhanced when the draft is increased.

The naturally lackadaisical kinetics of oxygen reduction reaction (ORR) in the cathode is one of the important factors that restrict the development of air-cathode microbial fuel cells (MFCs). In this work, the iron-nitrogen-carbon hierarchically nanostructured materials had been successfully fabricated by pyrolyzing glucose, iron chloride, and dicyandiamide with the aim of solving the issue. The obtained catalyst with an ultrathin nanostructure demonstrated an idiosyncratic electrocatalytic activity caused by the high content introduction of nitrogen and iron atoms, large surface area, which will offer sufficient active sites for improving the charge/mass transfer and reducing the diffusion resistance. Furthermore, with the increase of N dopant in the catalyst, better ORR catalytic activity could be achieved. Illustrating the N doping was beneficial to the ORR process. The high content of N, BET surface area caused by the N increasing could be responsible for the superior performance according to results of X-Ray photoelectron spectroscopy (XPS), Raman and Brunner-Emmet-Teller (BET) analysis. The ORR on the Fe–N3/C material follows 4e− pathway, and MFCs equipped with Fe–N3/C catalyst achieved a maximum power density (MPD) of 912 mW/m2, which was 1.1 times of the MPD generated by the commercial Pt/C (830 mW/m2). This research not only provided a feasible way for the fabrication of Pt-free catalyst towards oxygen reduction but also proposed potential cathode catalysts for the development of MFCs. [ABSTRACT FROM AUTHOR]

Mass spectrometers are sensitive tools used to identify and quantify both small and large analytes using the mass-to-charge ratios (m/z) of ions generated by electrospray ionization (ESI) or other methods. Ionization typically generates protonated or deprotonated forms of the analytes or adducts with adventitious metal ions derived from the spray solvent. The formation of a variety of ionized forms of the analyte as well as the presence of cluster ions complicates the data and can have deleterious effects on the performance of the mass spectrometer, especially under high salt or buffer conditions. To address this, a method involving a dual-electrode nanoelectrospray source has been implemented to rapidly and temporarily desalt the spray solution of interfering cationic and anionic species using electrophoretic transport from the spray tip. Peptides, proteins, and pharmaceutical drugs all showed improved results after the desalting process as measured by the quality of the mass spectra and the limits of detection achieved. Importantly ordinary phosphate buffers could be used to record protein mass spectra by nano-ESI. [ABSTRACT FROM AUTHOR]

Fluid flowing along underwater vehicles often acquire unsteady flow types such as flow separation and vortex shedding. The characteristics of unsteady flows around the underwater vehicle cause high frequency fluctuating pressure and noise on the vehicle rendering the underwater vehicle easily exposed. Studying the characteristics of flow separation on underwater vehicles, establishing accurate prediction methods for flow-induced noise and fast prediction formula based on test and simulation data are important for better understanding of the mechanism of flow separation-induced noise as well as fast prediction and control of underwater noise. In this study, the flow separation characteristics and fluctuating pressure induced by flow separation of underwater vehicles are studied. A simplified model composed of a cylinder, cone and other simple geometry is taken as the research object for water tunnel test and numerical analysis. We also discuss the appropriate numerical simulation method for predicting the flow separation and fluctuating pressure. The vortex distribution characteristics and flow separation mechanisms around the vehicle are analyzed and described based on the numerical method. The fitting function of pressure at different positions is established based on the flow characteristics, the experimental and numerical prediction data. Subsequently, the prediction formula of sound power level is verified. Results show that the flow separation characteristics and the numerical strategy employed in this study efficiently captured the flow filed and the surface fluctuating pressure characteristics of the simplified underwater vehicle. Findings from the numerical results and water tunnel data showed good prediction accuracy. The prediction results reflected the varying relationship of amplitude, frequency and the trend of data distribution. • A simplified underwater vehicle model is taken as the research object for water tunnel test and CFD analysis. • The vortex distribution characteristics and flow separation mechanism around the vehicle were analyzed and described based on the LES method. • A prediction function system that can predict the sound power level of underwater vehicles rapidly and accurately is obtained. [ABSTRACT FROM AUTHOR]