The design of a hydraulic pump or motor with a variable displacement could be much simpler, if a rotating valve plate could be used to vary the displacement. An essential aspect of the rotating valve plate is however that the passage of the cylinder ports from one kidney to the other often occurs while the pistons are moving. Experiments have revealed that this leads to high pressure spikes and cavitation. Because of this it is an unwritten rule that in hydraulic pumps and motors the passage of the so-called valving lands has to take place in the top and bottom dead centres.Against this rule there is a new hydraulic transformer developed (the Innas Hydraulic Transformer or IHT) in which the rotating valve plate is introduced again. Instead of varying the displacement the position of the valve plate now defines the pressure ratio between the load and the supply port. As will be shown this has a crucial effect on the valving land phenomena. Instead of increasing pressure pulsations and cavitation the rotating valve plate can now help to reduce these effects.

Through a series of incremental innovations, load sensing (LS) has become the current state-of-the-art in hydrostatic transmission technology. The Common Pressure Rail (CPR) is an alternative way to create a hydrostatic transmission. Although CPR systems offer considerable advantages over LS systems, they never really broke through. The main reason for this was the lack of a good solution to drive linear loads from a common pressure rail. The Innas Hydraulic Transformer (IHT) has been developed to fill this gap. It is a young component but has matured to a stage where a series production within the next two years should be possible. Because of its simple construction, its dynamic capacity, its low control power requirement and its efficiency it can be used to control both linear and rotary loads from a common pressure rail. With the IHT, the potential of CPR systems can finally be unleashed.

Thermoelectric power generation via Seebeck effect features an unique advantage in converting large amount of distributed and low-grade waste heat into electricity. Thermoelectric materials have become a hot topic of research in the field of new energy materials, guided by the high figure of merit ZT. Although various mid-temperature thermoelectric materials were discovered, the industrial application of these materials, especially in power generation applications, progressed very slowly. The staggering interface technology associated with thermoelectric device restricted the advance of thermoelectric conversion technology. In this review, the bottleneck issues of utilizing Bi 2 Te 3-based devices for power generation were used as an example to illustrate the critical interface technologies. The key issues at designing electrode contact interfaces were summarized, including low contact resistance, high bonding strength, and superior thermal chemical stability at high temperature. The recent progress on the metallization and interfacial barrier layer for typical materials of Bi 2 Te 3 , PbTe and CoSb 3 were also reviewed.

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