Abstract: A displacer assembly for a Stirling cycle system includes a displacer and a synchronous linear electric motor linked so as to drive the displacer. The electric motor features at least one stator assembly having first and second soft-magnetic pole pieces defining therebetween a gap. The width of the gap is oriented perpendicular to an axis of movement of the motor, and the stator assembly is constructed so as to generate a magnetic field aligned primarily parallel to the width of the gap. The motor also includes at least one compound permanent magnet system located within the gap. The compound permanent magnet system has a first section magnetized in a first direction parallel to the width of the gap and a second section axially displaced from the first section magnetized in a direction opposite to the first direction. The result of this structure is that the electric motor operates as a magnetic spring which, when no power is supplied to the motor, returns the displacer to a predefined rest position.

Abstract: A synchronous reciprocating electric machine includes a first magnet system having first and second opposing surfaces forming between them a gap, and a second magnet system mounted within the gap so as to be displaceable relative to the first magnet system along a line of travel through the gap. The the first magnet system is configured for generating a magnetic field, referred to as the "gap field", directed across the gap primarily perpendicular to the first surface. The second magnet system includes two magnetic elements configured to generate equal but opposite magnetic fields primarily perpendicular to the first surface. These magnetic elements are spaced from each other along the line of travel by a distance b, where b>0. One of magnet systems produces a non-alternating magnetic field and the other is a coil assembly for producing an operating magnetic field.

Abstract: A synchronous twin reciprocating piston apparatus includes a cylinder and a number of stator assemblies mounted in fixed relation thereto. The stator assemblies are constructed so as to generate a radial magnetic field in a number of regions near to each end of the cylinder. The apparatus also includes a pair of piston-magnet assemblies, each having a piston slidable within an end of the cylinder, and a number of compound permanent magnet systems located within the regions. Each compound permanent magnet system includes a first section magnetized in a direction radial relative to the cylinder axis and a second section, axially displaced from the first, magnetized in the opposite direction. When the stator assemblies are excited with an alternating current, the piston-magnet assemblies reciprocate axially relative to said cylinder, and synchronously with the frequency of the applied current. The pistons then generate a pulsating pressure within the cylinder.

Abstract: The invention provides a process for forming a ceramic coating on a valve metal selected from the group consisting of aluminum, zirconium, titanium, hafnium and alloys of these metals. The process comprises the steps of (a) immersing the metal as an electrode in an electrolytic bath comprising water and a solution of an alkali metal hydroxide; (b) providing an opposite electrode immersed in or containing the electrolyte liquid; (c) passing a modified shaped-wave alternate electric current from a high voltage source of at least 700 V through a surface of the metal to be coated and the opposite electrode, thereby causing dielectric breakdown, heating, melting, and thermal compacting of a hydroxide film formed on the surface of the metal to form and weld a ceramic coating thereto, and (d) changing the composition of the electrolyte while the ceramic coating is being formed, the change being effected by adding an oxyacid salt of an alkali metal.