A method of determining bearing preload by vibration measurement including mounting the bearing on a vibration tester, the outer ring clamped preventing rotation, mounting a sensor proximate the outer ring to measure vibration, the bearing inner ring rotated to excavate eigen-frequencies, the measured vibration data transmitted from the sensor to a computer workstation, the computer workstation performs a numerical FFT transforming data to Frequency Domain, spectral data from the FFT analyzed with the computer workstation, a peak detection algorithm determines the peaks that are the various modes of the outer ring, the modes are sorted and main modes identified, numerical relationship is obtained for each mode between the resonance and preload, the mode relationships are compared to one or more references, a match between the numerical relationships for each mode and the ideally referenced graph modes indicates a correct preload is determined. Also, a system for carrying out the method.

A measurement method includes: a physical quantity acquisition step of acquiring, based on observation information obtained by at least one observation device that observes first to N-th observation points of a structure arranged along a second direction intersecting a first direction in which a moving object moves along the structure, physical quantities at the first to N-th observation points; and an action calculation step of calculating actions x.sub.1 to x.sub.N on the first to N-th observation points based on the acquired physical quantities at the first to N-th observation points, on the assumption that, when a function indicating a correlation between an action x.sub.j on a j-th observation point and an action that the action x.sub.j has on an i-th observation point is set as y.sub.ij, an acquired physical quantity at the i-th observation point is equal to a sum of values of functions y.sub.i1 to y.sub.iN.

A measurement method includes: a physical quantity acquisition step of acquiring, based on observation information obtained by at least one observation device that observes first to N-th observation points of a structure arranged along a second direction intersecting a first direction in which a moving object moves along the structure, physical quantities at the first to N-th observation points; and an action calculation step of calculating actions x.sub.1 to x.sub.N on the first to N-th observation points based on the acquired physical quantities at the first to N-th observation points, on the assumption that, when a function indicating a correlation between an action x.sub.j on a j-th observation point and an action that the action x.sub.j has on an i-th observation point is set as y.sub.ij, an acquired physical quantity at the i-th observation point is equal to a sum of values of functions y.sub.i1 to y.sub.iN.

The present disclosure provides systems, methods, and apparatuses for estimating tension in post-tensioned rods, such as anchor rods that support structural steel to concrete. A method of estimating tension in a target post-tension rod may include selecting a plurality of post-tensioned rods and modeling tension for the plurality of post-tensioned rods as a function of frequency differences between a first and a second modal frequency and cantilever length of each rod. The method may further include measuring the length of a cantilever of the target post-tensioned rod, determining first and second modal frequencies of the target post-tensioned rod, and determining a frequency difference between the first and second modal frequencies. The method may further include estimating tension in the target post-tensioned rod based on at least the model.

The present disclosure provides systems, methods, and apparatuses for estimating tension in post-tensioned rods, such as anchor rods that support structural steel to concrete. A method of estimating tension in a target post-tension rod may include selecting a plurality of post-tensioned rods and modeling tension for the plurality of post-tensioned rods as a function of frequency differences between a first and a second modal frequency and cantilever length of each rod. The method may further include measuring the length of a cantilever of the target post-tensioned rod, determining first and second modal frequencies of the target post-tensioned rod, and determining a frequency difference between the first and second modal frequencies. The method may further include estimating tension in the target post-tensioned rod based on at least the model.

The present disclosure provides systems, methods, and apparatuses for estimating tension in post-tensioned rods, such as anchor rods that support structural steel to concrete. A method of estimating tension in a target post-tension rod may include selecting a plurality of post-tensioned rods and modeling tension for the plurality of post-tensioned rods as a function of frequency differences between a first and a second modal frequency and cantilever length of each rod. The method may further include measuring the length of a cantilever of the target post-tensioned rod, determining first and second modal frequencies of the target post-tensioned rod, and determining a frequency difference between the first and second modal frequencies. The method may further include estimating tension in the target post-tensioned rod based on at least the model.

An optomechanical pressure-measurement system measures pressure in the range of 10.sup.−6 Pa-10.sup.−2 Pa by measuring various properties of a vibrational mode of an ultra-thin membrane member. With independent measurements of the thickness and density of the membrane, in addition to the measured vibration mode properties, the system can operate as a primary pressure sensor. The membrane member is mounted on a vibration-isolated mount and is excited by a drive force. A laser beam impinges on the excited membrane, and an optical phase detector detects the amplitude of the oscillations, as well as parameters of the laser beam affected by the membrane vibration. In one embodiment, a mechanical damping is computed based on the amplitude or frequency shift (depending on the pressure range), and the pressure based on the ring-down time of the membrane vibration mode.

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.

A method for testing a bond using a bond tester apparatus, the method comprising the steps of applying a mechanical force to the bond, determining, by a sensor component comprised by the bond tester apparatus, the applied force to the bond by measuring, by the sensor component, a displacement of the sensor component caused by the applied force and calculating, by the sensor component, the applied force on the basis of a first component which comprises a direct relationship with the measured displacement and on the basis of at least one of a second component, a third component and a fourth component.

An input-side control device includes: a feedback controller that generates a first control input signal for eliminating the difference between a model speed signal ωm and a speed detection signal ω by using the signal difference between a higher order torque command signal Tref and an axial torque detection signal Tsh to generate the model speed signal ωm which corresponds to the rotational speed of an inertial body having a set moment of inertia Jset moving under a torque corresponding to the signal difference; a feed-forward controller that generates a second control input signal by multiplying the signal difference by k.Math.Jdy/Jset; and a low-pass filter that generates a torque command signal Tr from a signal obtained by combining the outputs of the controllers and attenuating components at a higher frequency than a cut-off frequency fc set in the vicinity of the resonant frequency.