Abstract
In wireless power transfer systems, if the driver is not capable of dynamically adapt its own switching frequency, small environmental changes or even slight deviations in circuit parameters may prevent the complete system from working properly when the optimal resonance frequency moves towards new values. In this paper, we propose an adaptive system suitable for underwater wireless applications in sea water. The output voltage is regulated using the wireless power link, avoiding the need for additional wireless interfaces. Our complete system includes the power driver, coupling coils, rectifier, and two micro-controllers. The regulation is accomplished by digital load modulation, observable at the input by means of current sensing at the power supply. Experimental results demonstrate a class-D driver with a series-series resonant topology working in saline water, delivering power between 1.6 and 2.4 W. The regulated voltage is 7.5 V with error less than 7.2 % in the load range of 30 to 37 Omega and 6 to 10 V power supply variation. The switching frequency is adjusted within the range of 7 kHz deviation (-7%).

Abstract
This work presents a new topology for the matching networks of an underwater wireless power transfer system. A class-D driver is used in resonance at fundamental and third harmonic frequencies. The double resonance helps reducing the reverse voltage stress at the diode rectifier. We present the analytical derivation of the proposed network and demonstrate the design procedure with an example. We also show that additional degrees of freedom can be acquired with the proposed topology, which improves the design space for time-varying operation conditions of our application, such as the load changing when a battery is being recharged. The performance of our topology is compared to most conventional approaches, such as the series-series and series-parallel networks, revealing a good compromise between power delivery and efficiency across a wide load range.

Abstract
The present work addresses the design of an electronic system for powering autonomous underwater vehicles (AUVs). We report the study and implementation of a system developed for transmitting and receiving wireless power in water from a docking station to an AUV. A simplified analysis is presented regarding the operation of a class-D power driver in a series-series inductive resonant coupling topology. We further investigate the compromise between link efficiency and power delivery of the system to circumvent the reduced power output capability. Simulation results are provided as well as measurement data validated using circuit prototypes in an experimental setup with a structure similar to the docking station of the AUV filled with salt water.

Abstract
In this work we present a study addressing the load modulation for wireless power transfer in underwater applications. A voltage-mode class-D in a series-series resonance topology is analyzed with simplified equations provided to describe the operation of the wireless power system, including the influence of the load on the primary side. The analysis is validated through simulation results provided for a resistive load modulation using component SPICE models, including the characterization of coupling coils in salt water.

Abstract
This is a case study on leadership, a topic which has been much debated in the literature, as solutions for many diverse situations are still lacking and seem to escape us. The case describes how an entrepreneurial wood veneer factory operates, in the USA, with images included of a number of operations. The manager-owner took us on a guided tour from raw material (logs) to finished product (veneer wood). Waste is minimized at the factory in a very stream-lined operation which has a minimal amount of managers in place. Each worker is responsible for his or her job, done to perfection, as one task rolls on to the next, without stopping. The attitude of the innovative servant-type leadership in place is that "win-win" situations are better for all, and there is enough profit to go around. Servant-leadership-type leaders exist to serve employees and exercise minimal management control. At this firm there are no self-serving managers. Rather, mature and great working relationships are developed. Being greedy would mean that unions would have to be brought in. At this firm that was not necessary, by request of the employees themselves. Hispanic workers are very good and are cherished at this firm, in the heart of the USA. As leadership is dependent on culture, the discussion also includes references to cultural aspects relevant to management. The story is thus of a positive firm with positive leadership and subordinates. We conclude that employees who have emigrated from poorer countries in search of a better lifestyle may indeed make excellent workers, despite what some political leaders have announced in the media. We have found evidence that Spanish-speaking individuals do not only work well under autocratic leadership, as portrayed by the literature. Our study is thus revealing of a new cultural-type involving workers working outside their home countries. Under different leaders, in different countries and environments, certain workers are prepared to go the "extra mile" and behave in a completely different way as to what is expected from them in their home countries. This is surprising and may have important implications for multinational firms worldwide.

Abstract
In this work we focus on the influence of salt water as the medium between two coupling coils to design a wireless power transfer system. An electrical circuit model and an adequate characterization approach is presented to account for the power losses in the conductive medium. Optimum values for the load and efficiency of the power link are determined. Experimental results are provided to compare the performance of the coupling coils between different coupling mediums (air, fresh and salt water).