Apparatus and method for on-linebarkhausenmeasurement
Apparatus and method for measuring the Barkhausen signal of a moving magnetic film, ribbon or fiber wherein first and second stationary electromagnet coils are arranged and separated by a distance, d, along the path of movement of the film, ribbon or fiber. The first and second coils are energized in a manner to generate first and second opposing DC magnetic fields through which the moving film, ribbon or fiber passes along its path of movement. As the film, ribbon or fiber moves through the first and second opposing magnetic fields at a velocity, v, it experiences one complete cycle of magnetization in a period of time equal to d/v. A stationary third signal pick-up coil is disposed between the first and second coils to detect the Barkhausen signal from the moving film, ribbon or fiber. The pick-up coil typically is disposed midway between the first and second coils where the Barkhausen signal will be approximately maximum.
Method and apparatus for bone sensing
The invention discloses an improved bone conduction sensor capable of use within a voice sound transmitting apparatus. The bone conduction sensor is adapted for placement in the external auditory canal of the user in a nonocclusive fashion. The bone conduction sensor has a contoured surface adapted-to fit against a wall of the external auditory canal increasing the surface area contact between the bone conduction sensor and the wall of the external auditory canal. The bone conduction sensor may also be associated with one or more contact sensors adjacent the bone conduction sensor for determining contact between the bone conduction sensor and the wall of the external auditory canal. In addition, the invention provides for the bone sensing element to be separated from the circuit portion of the bone conduction sensor so that the circuitry may be removed to the behind the ear portion of the earpiece.
Apparatus and method for driving an ultrasonic transducer
A method and apparatus for electronically driving an ultrasonic acoustic transducer. The transducer is operable in two modes; in a first mode, the lock-in frequency of the transducer is determined; in a second mode, the lock-in frequency determined in the first mode is used to modulate a tone-burst pulse to drive the transducer in an efficient manner. Operating in the first mode, the lock-in frequency is determined by exciting the transducer with a series of tone bursts, where each tone burst comprises an electronic pulse modulated by a tone of one frequency selected from a range of frequencies, and measuring the response of the transducer to each tone burst. In an alternative embodiment, the excitation of the transducer in the first mode is provided by a signal whose frequency is swept over a range. The response of the transducer is sampled at various times during the sweep. The lock-in frequency is chosen by examining the responses and choosing the frequency which gives the best response. Operating in the second mode, the transducer is driven with an electronic tone burst generated by modulating said an electronic pulse with a tone of the determined lock-in frequency.
Apparatus and method for transient thermal infrared spectrometry
A method and apparatus for enabling analysis of a material (16, 42) by applying a cooling medium (20, 54) to cool a thin surface layer portion of the material and to transiently generate a temperature differential between the thin surface layer portion and the lower portion of the material sufficient to alter the thermal infrared emission spectrum of the material from the black-body thermal infrared emission spectrum of the material.
It is very important to control any risk of instability of embankment during vacuum construction, the simulation vacuum preloading method using tri-axial apparatus is proposed to predict the behavior of soft soil improvement in the labora- tory, as well as to make this method become familiar and easier in the future. The tri-axial apparatus is used instead of the large-scale one, which has been performed by Bergado (1998) and Indaratna (2008). The tri-axial test on small size specimen can be carried out in one week compared to the large-scale apparatus takes one month for big specimen. In addition, the lateral deformation as well as the shear strength increase with time can determine accurately.
Referring to FIGS. 15 and 16, the preferred mounting arrangement for the toroidal transformer cores 10, 12, 14 is such that their axes are mutually perpendicular. This minimises the magnetic cross coupling between the cores that would otherwise reduce the discrimination of the conductivity measurement. According to one embodiment, the mutually perpendicular mounting arrangement of the toroidal transformer cores is achieved with the loop 28 comprising two bends 48 at 45 degrees. The first, energising transformer core 10 and second, current sensing transformer core 12 are threaded onto the loop 28 such that they have a perpendicular orientation. The third, reference circuit sensing transformer core 14 is mechanically attached by any suitable means to the central portion of the loop 28 such that its axis is perpendicular to both transformer cores 10,12. In the embodiment shown in FIGS. 15 and 16, transformer core 14 is attached to loop 28 by means of a non-conducting mounting block 49 moulded or machined to securely hold the core 14 at right angles to the loop 28. A simple non-conducting clip or loop, such as a plastic ratchet tie, is used to hold this assembly tightly against loop 28.