Abstract:
Hundreds of thousands of concrete bridges and hundreds of billions of tons of concrete require characterization with time for corrosion. Accordingly, protocols for rapid testing and improved field characterization systems that automatically triangulate electrical resistivity and half-cell corrosion potential measurements would be beneficial allowing discrete/periodic mapping of a structure to be performed as well as addressing testing for asphalt covered concrete. Further, it is the low frequency impedance of rebar in concrete that correlates to corrosion state but these are normally time consuming vulnerable to noise. Hence, it would be beneficial to provide a means of making low frequency electrical resistivity measurements rapidly. Further, prior art techniques for electrical rebar measurements require electrical connection be made to the rebar which increases measurement complexity/disruption/repair/cost even when no corrosion is identified. Beneficially a method of determining the state of a rebar without electrical contact is taught.
Abstract:
A current source circuit flowing an output current to at least one detection element including a first terminal to which a first voltage is supplied and a second terminal being connected to the current source circuit includes a reference resistance, a current mirror circuit including at least one first transistor and at least one second transistor, and a control circuit controlling a voltage of a common wire that is connected to a terminal provided at the first transistor and a terminal provided at the second transistor such that a voltage of a terminal provided at the reference resistance comes to be equal to a reference voltage.
Abstract:
A crystal unit includes: a crystal blank; an excitation electrode formed on the crystal blank and excites a main vibration of the crystal blank; a housing that accommodates the crystal blank; and a sub-vibration electrode formed on the housing and excites a sub-vibration of the crystal blank.And a method for inspecting a crystal unit, the method includes: generating a sub-vibration in a crystal blank by applying an input signal to a sub-vibration electrode formed on a housing, which accommodates the crystal blank, via external electrodes which are electrically coupled to the sub-vibration electrode and formed on the outer surface of the housing; obtaining an output of the crystal unit via the external electrodes; obtaining frequency characteristics of impedance between the external electrodes based on the output; and comparing the obtained frequency characteristics with the reference frequency characteristics indicating the quality of the crystal unit.
Abstract:
A bi-state bifurcation-based control system and method for nonlinear resonators, which utilizes a control loop to servo on the edge of the bifurcation jump, either at the maximum “on” point prior to the Duffing bifurcation jump or along the rising edge of the parametric bifurcation.
Abstract:
Aspects of the present disclosure are directed to force sensors. As may be implemented in accordance with one or more embodiments, an apparatus includes a force-responsive component having a resonant frequency, and a circuit that compensates for variations with the force-responsive component. The force-responsive component moves in response to an applied force, in accordance with a spring constant that is susceptible to fluctuation. The compensation circuit determines Brownian motion of the force-responsive component at the resonant frequency based on temperature, and generates an output based on the determined Brownian motion and movement of the force-responsive component. Such an output is indicative of force applied to the apparatus.
Abstract:
Hundreds of thousands of concrete bridges and hundreds of billions of tons of concrete require characterization with time for corrosion. Accordingly, protocols for rapid testing and improved field characterization systems that automatically triangulate electrical resistivity and half-cell corrosion potential measurements would be beneficial allowing discrete/periodic mapping of a structure to be performed as well as addressing testing for asphalt covered concrete. Further, it is the low frequency impedance of rebar in concrete that correlates to corrosion state but these are normally time consuming vulnerable to noise. Hence, it would be beneficial to provide a means of making low frequency electrical resistivity measurements rapidly. Further, prior art techniques for electrical rebar measurements require electrical connection be made to the rebar which increases measurement complexity/disruption/repair/cost even when no corrosion is identified. Beneficially a method of determining the state of a rebar without electrical contact is taught.
Abstract:
A force sensor (10) is forced from a vibrating beam (11), an excitation piezoelectric device (12) to cause a vibration in the beam at its resonate frequency and a measurement piezoelectric device (12) to measure the frequencies being indication of the force applied to the beam (11). The excitation and measurement piezoelectric devices (12) are attached to the beam adjacent to each other at one end of the beam (11).
Abstract:
The disclosed sensor chip includes a substrate and a moving member coupled to the substrate and disposed for movement relative to the substrate. The moving member moves relative to the substrate in a first direction and in a second direction in response to movement of the substrate. The first direction is different than the second direction. The moving member includes a plurality of receptors. The receptors are configured for selectively binding to a first measurand.
Abstract:
A dynamometer comprising a pair of similar leaf springs (4 and 5), lying in approximately the same plane, and at least one additional leaf spring (24). The outer part of the additional leaf spring (24) and any other supplementary leaf springs (6, 7, 19, and 20) replacing the single leaf spring and being fastened to the frame (1) and the inner part being fstened to the middle block (8). The leaf springs (6, 7, and 24) lie in a plane approximately parallel to that of the first pair of leaf springs (4 and 5), while the supplementary leaf springs (19 and 20) lie in the same plane as the first pair of leaf springs (4 and 5). An elastic rod (9 and 10) is attached to the middle of each of the leaf springs (4 and 5), respectively, and a force-measuring device (11) is located between these rods. The force being measured is exerted perpendicularly to the planes of the leaf springs (4 through 7, 19, 20, and 24) on the middle block (8) as a compressive or tractive force, and the middle block is displaced in a parallel direction by the leaf springs. At the same time, the rods (9 and 10) are either spread apart or forced closer together, and the force-measuring device (11) is affected accordingly.
Abstract:
A technique is described for tailoring the configuration of electrodes on a piezoelectric beam such that the tendency of the beam to vibrate in a predetermined flexure mode is enhanced. The mode has a predetermined longitudinal strain versus longitudinal position profile. At least two electrodes are mounted on the beam, and the configuration of at least one electrode varies as a function of longitudinal position, such that when a voltage difference is applied between the electrodes, the longitudinal force produced by the electrodes, as a function of longitudinal position, approximates the longitudinal strain versus longitudinal position profile. The configuration may be varied by varying the width of the electrode or the position of the electrode on the underlying beam surface.