High-speed blades are often prone to fatigue due to severe blade vibrations. In particular, synchronous vibrations can cause irreversible damages to the blade. Blade tip-timing methods (BTT) have become a promising way to monitor blade vibrations. However, synchronous vibrations are unsuitably monitored by uniform BTT sampling. Therefore, non-equally mounted probes have been used, which will result in the non-uniformity of the sampling signal. Since under-sampling is an intrinsic drawback of BTT methods, how to analyze non-uniformly under-sampled BTT signals is a big challenge. In this paper, a novel reconstruction method for non-uniformly under-sampled BTT data is presented. The method is based on the periodically non-uniform sampling theorem. Firstly, a mathematical model of a non-uniform BTT sampling process is built. It can be treated as the sum of certain uniform sample streams. For each stream, an interpolating function is required to prevent aliasing in the reconstructed signal. Secondly, simultaneous equations of all interpolating functions in each sub-band are built and corresponding solutions are ultimately derived to remove unwanted replicas of the original signal caused by the sampling, which may overlay the original signal. In the end, numerical simulations and experiments are carried out to validate the feasibility of the proposed method. The results demonstrate the accuracy of the reconstructed signal depends on the sampling frequency, the blade vibration frequency, the blade vibration bandwidth, the probe static offset and the number of samples. In practice, both types of blade vibration signals can be particularly reconstructed by non-uniform BTT data acquired from only two probes.

In this paper, a novel simultaneous wireless power and data transfer (SWPDT) system is proposed for underwater wireless sensor networks. A pair of coils is used to establish forward power transfer and bidirectional data transfer links based on coupled magnetic resonance. While transmitting power to the load, the forward power waves are also used as the carrier for data transfer, thereby avoiding the use of an additional carrier source on the power transmitter-side. An improved double-LCC double-CLC topology is presented to achieve both impedance matching and wave filtering of the SWPDT system in full-duplex mode, instead of using additional wave trappers, transformers or tap coils. Compared with previous works, the proposed system can simultaneously achieve high power gains, low mutual interference and simple circuit structure. Moreover, to deal with the conflicts between the power gains and the bandwidths of the channels, an improved multi-objective optimization method is proposed for the SWPDT system. Using this method, the Pareto optimal solutions of the system parameters can be found and the comprehensive performance of the SWPDT system can be further improved. Finally, an experimental prototype is established, which achieves full-duplex wireless power and data transfer, with a maximum load power of 23.1W, a forward data transfer rate of 20kbps and a backward data transfer of 300kbps. There is almost no interference between power and data transfer. The experimental results show that the proposed SWPDT system has good application prospects in underwater sensor node charging and full-duplex communication.

Sub-resonances often happen in wireless power transmission (WPT) systems using coupled magnetic resonances (CMR) due to environmental changes, coil movements or component degradations, which is a serious challenge for high efficiency power transmission. Thus self-tuning is very significant to keep WPT systems following strongly magnetic resonant conditions in practice. Traditional coupled-mode ways is difficult to solve this problem. In this paper a two-port power wave model is presented, where power matching and the overall systemic power transmission efficiency are firstly defined by scattering (S) parameters. Then we propose a novel self-tuning scheme based on on-line S parameters measurements and two-side power matching. Experimental results testify the feasibility of the proposed method. These findings suggest that the proposed method is much potential to develop strongly self-adaptive WPT systems with CMR.

Maintainability of a mechanical system is one of the system design parameters that has a great impact in terms of ease of maintenance. In this paper, a methodology of facility layout optimum design for maintainability of a ship cabin is presented as a way to improve the efficiency and quality of maintainability design. The maintenance operating space, amount of hoisting, balance of cabin, distance requirement and personnel movement distance are all taken into account, and treated as objective functions. The mechanical functional constraints and some important layout experience are also considered and formulated as constraints. Thus, the mathematical model for maintainability layout combinatorial optimisation is constructed. According to the characteristics of maintainability-based facility layout problem, the particle swarm optimisation algorithm developed by Eberhart and Kennedy is modified to enhance the computational efficiency and solution accuracy. A hybrid position updating method is used to solve the optimisation problem with both continuous and discrete variables. The dynamic neighbourhood structure, dynamic inertia weight and adaptive mutation mode are modified to effectively solve the optimisation problem with multiple peak values. Finally, the methodology proposed is illustrated by simulation case and engineering application, and the results suggest that the methodology is effective.

One of the greatest challenges to power embedded devices using magnetically coupled resonant wireless power transfer (WPT) system is that the amount of power delivered to the load is very sensitive to load impedance variations. Previous adaptive impedance-matching (IM) technologies have drawbacks because adding IM networks, relay coils, or other compensating components in the receiver-side will significantly increase the receiver size. In this paper, a novel frequency-tracking and impedance-matching combined system is proposed to improve the robustness of wireless power transfer for embedded devices. The characteristics of the improved WPT system are investigated theoretically based on the two-port network model. Simulation and experimental studies are carried out to validate the proposed system. The results suggest that the frequency-tracking and impedance-matching combined WPT system can quickly find the best matching points and maintain high power transmission efficiency and output power when the load impedance changes.