Abstract: The present invention concerns a downhole cable or control line detection tool. More particularly, but not exclusively, this invention concerns a method and apparatus for the downhole detection of a cable or control line associated with the external wall of a well casing. A downhole tool for the detection of downhole cable or control lines is provided. The downhole tool comprises an eddy current sensor, the eddy current sensor being arranged to be proximate to the internal wall of a well casing. The eddy current sensor is arranged for pulsed operation. The downhole tool further comprises a mechanism for rotating the eddy current sensor, with an axis of rotation parallel with the longitudinal axis of a well casing.

Abstract: The present invention concerns a firing switch for a downhole ballistics device. More particularly, but not exclusively, this invention concerns a firing switch for a downhole ballistics device and a method of operating the firing switch. The invention also concerns various safety features relating to the firing switch. A firing switch arrangement for a downhole perforating gun (26, 28, 30, 32, 34) is provided, and comprises a firing switch (26?, 28?, 30?, 32?, 34?), and a detonator (40), the detonator arranged to be activated in response to an electrical signal from the firing switch. A removable safety tab (42) is associated with the detonator, the removable safety tab arranged to provide a short circuit to the detonator, such that the short circuit is removed if the removable safety tab is removed.

Abstract: The present invention concerns a downhole cable or control line detection tool. More particularly, but not exclusively, this invention concerns a method and apparatus for the downhole detection of a cable or control line associated with the external wall of a well casing. A downhole tool for the detection of downhole cable or control lines is provided. The downhole tool comprises an eddy current sensor, the eddy current sensor being arranged to be proximate to the internal wall of a well casing. The eddy current sensor is arranged for pulsed operation. The downhole tool further comprises a mechanism for rotating the eddy current sensor, with an axis of rotation parallel with the longitudinal axis of a well casing.

Abstract: The present invention concerns a firing switch for a downhole ballistics device. More particularly, but not exclusively, this invention concerns a firing switch for a downhole ballistics device and a method of operating the firing switch. The invention also concerns various safety features relating to the firing switch. A firing switch arrangement for a downhole perforating gun (26, 28, 30, 32, 34) is provided, and comprises a firing switch (26?, 28?, 30?, 32?, 34?), and a detonator (40), the detonator arranged to be activated in response to an electrical signal from the firing switch. A removable safety tab (42) is associated with the detonator, the removable safety tab arranged to provide a short circuit to the detonator, such that the short circuit is removed if the removable safety tab is removed.

Abstract: In order to check the authenticity of a banknote or other such document it is printed with two patches of magnetisable ink, and each patch is magnetised to present a multipole sequence of alternating polarity. If the document is folded to bring the two patches together and then rubbed to and fro in the direction of the pole sequences, they will be subject to alternating forces of attraction and repulsion which can be sensed through the fingertips and gives the impression of a physically rippled texture notwithstanding that the patches actually have a smooth surface. The presence or absence of this effect can therefore be used to distinguish between a genuine document bearing such magnetised patches and a counterfeit which may be visually identical but lacks the correct magnetisation. In a variant only one of the patches is printed on the document itself and the other is on a separate “key” device which is rubbed over it to test for the presence of the correct magnetisation.

Abstract: A composition, method and apparatus for ink jet deposition of structures are described. Structures which may be deposited have many advantages as a result of their small scale. This is believed to be a result of the sub-micron sized loading used in the composition. Solid Oxide Fuel Cells (SPFCs) are a particular structure which may advantageously be deposited.

Abstract: A method of fabricating a magnetic tag having a plurality of information bits on its surface where some or all of the information bits are formed by depositing magnetic material onto the surface by means of an electroless deposition reaction.