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We prepared micro–nano TiO2 microspheres by hydrothermal method, mixed with epoxy resin (ER) and spreaded onto a glass slide to prepare a superhydrophobic coating. The coating and microspheres were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD), scanning electron microscope (SEM), tape peeling test and contact angle meter. Results showed that the coating had contact angle (CA) and sliding angle (SA) of 160.7° and 3.2°, respectively. Water droplets can roll freely on its surface, with evident lotus leaf effect. The coating can withstand 100 times of tape peeling test. Compared with ordinary glass, the dust on the surface of superhydrophobic glass can roll off with water droplets and has evident self-cleaning effect.

To the problem of the unknown underwater target detection, according to the feature that the underwater target radiated noise contains the stable line spectrum, a weighted method based on the main-to-side lobe ratio (MSLR) is proposed for broadband beam-forming. This weighted method can be implemented by using the following steps. Firstly, optimize the spatial spectrum of each frequency unit by the second-order cone programming (SOCP), and obtain the optimized spatial spectrum with lower side lobe. Secondly, construct weighting factors based on the MSLR of the optimized spatial spectrums to from weight factors. Lastly, cumulate the spatial spectrum of each frequency unit via the weight statistical method of this paper. This method can restrain the disturbance of background noise, enhance the output signal-to-noise ratio (SNR), and overcome the difficulty of traditional four-dimensional display. The theoretical analysis and simulation results both verify that this method can well enhance the spatial spectrum of line spectrum units, restrain the spatial spectrum of background noise units, and improve the performance of the broadband beam-forming.

The preparation of superhydrophobic coatings has been extensively researched, but their practical applications are limited by complicated preparation processes and poor mechanical durability. This study proposed a simple, low-cost method of preparing superhydrophobic coatings. A nano-silica dispersion was sprayed onto a semi-cured silicone-modified polyurethane resin through a two-step spraying method. Subsequently, these materials solidified together to successfully prepare a superhydrophobic coating with 159° contact angle and 2° sliding angle. The prepared silica/silicone-modified polyurethane (SiO2/SiPU) superhydrophobic coating showed superhydrophobic property after being cyclically rubbed for 30 cycles on 1000-mesh sandpaper under a load of 200 g. The coating further exhibited good corrosion resistance when placed in strong acid and alkali environments and excellent self-cleaning properties in air. This simple and environmentally friendly approach may have enormous application potential in many fields.

The hydrophone which use DFB fiber laser as sensing element has many advantages such as thin diameter, high sensitivity, easy to multiplex array, wide dynamic range, immunity to electromagnetic interference and no need of impedance matching. A 4-element fiber laser hydrophone towed linear array is studied. A sleeve with grooves type fiber laser hydrophone is designed and realized. The sensitivity experiment of the hydrophone element shows that the sensitivity is about -135dB（re 1rad/μPa）in the range of acoustic frequency from 20Hz to 1000Hz, and the amplitude fluctuate of the frequency response curve is less than±1.5dB. Based on the hydrophone of this structure and the WDM technology, the 4-element fiber laser hydrophone towed linear array that is encapsulated with polyurethane sleeve is established, and its diameter is 15mm. The experiments of the hydrophone towed linear array in the lake test show that the localization and tracking of the target can be realized by the towed linear array.

A new vibration analyzing system based on the S3C6410, a 16/32-bit ARM 11 CPU and the AD7606, an 8-channel high-speed simultaneous 16-bit analog to digital converter (ADC) is presented. The design of hardware is described, in which the IDT72V265, a 16K x 18-bit synchronous FIFO was applied to realize the continuous and real-time data transmission from ADC output register to SDRAM through the data bus of S3C6410. Embedded Linux 3.0 operating system was transplanted, and hardware drivers which provide up-layer Linux applications the interface of ADC control and data transmission have been developed. In the upper computer, the MFC application with functions to receive, save, process and display data from the lower acquisition system was fulfilled. The test results showed that acquisition data was accurate and the system turned out to be reliable at the highest sampling rate of AD7606.

An adaptive inverse beamforming and CLEAN image processing method (IBF-CLEAN) was put forward to cancel tow ship noise. The tow ship noise is a wideband, spatially wide distributing noise with high intensity. It is the primary interference for towed line array. Inverse beamforming (IBF) can be used to cancel such directional noise. Iterative use of IBF can eliminate the reflection paths of the tow ship noise which comes from slightly different directions. But because the reflection paths of the tow ship noise are adjacent to each other, it's difficult for IBF to cancel the tow ship noise completely. Then an image processing method, CLEAN, was used to improve the results further. The sidelobes of the mainlobes and environmental noise can be cancelled efficiently by CLEAN. Combination of IBF and CLEAN makes use of the advantages of these two methods. IBF-CLEAN is a novel method which can improve the time/bearing display.

The joint effect of space and time correlation on the underwater acoustic Multiple-Input-Multiple-Output (MIMO) channel capacity is studied using the multipath space-time correlation model with a moving transmit array and a stationary receive array. The space-time correlation function of the uniform liner array is generated, which can be expressed as the production of the space correlation function and the time correlation function, so the space-time joint correlated complex Gaussian variates can be generated by firstly generating n/sub T/*n/sub R/ independent random variates with the desired autocorrelation function, and then multiplied by the square root of their cross-correlation matrix. Using Monte Carlo simulations, the effect of space and time correlation on the underwater acoustic MIMO capacity is studied by the parameters of transmitter velocity, array element spacing, and elevation angle spread. It is shown from the simulation results that in the case of a poor scattering environment and not sufficiently large element spacing, when n transmitter elements and n receiver elements are employed, the outage capacity will not increase linearly with the increasing of n, and large capacity gains can only be obtained in a rich scattering environment and with sufficiently large element spacing, and the effect of transmitter velocity on the capacity depends on the block length T, when T/spl Gt/T/sub coh/, capacities with different transmitter velocity will be the same.