The disclosure provides a method for identifying a modal frequency of a beam bridge by considering influence of environmental temperature. The method includes the following steps: installing a sensor on a newly-built beam bridge without damage, measuring a dynamic response of the nearn bridge cinder ambient excitation, recording temperature data, processing by a modal parameter identification method to obtain a modal frequency value at the temperature, and titarling from a modal frequency corresponding to the temperature, carrying out iterative calculation to obtain the modal frequency at any temperature. The modal frequency value at any temperature is obtained by arranging a small number of sensors and canying out a small number of tests, so that the influence of the temperature on the modal frequency is quantified, furthermore, the part of environmental influence is eliminated in future damage evaluation of the beam bridge, which allows for a more accurate isamage evaluation rttsult,

The disclosure provides a method for identifying a modal frequency of a beam bridge by considering influence of environmental temperature. The method includes the following steps: installing a sensor on a newly-built beam bridge without damage, measuring a dynamic response of the nearn bridge cinder ambient excitation, recording temperature data, processing by a modal parameter identification method to obtain a modal frequency value at the temperature, and titarling from a modal frequency corresponding to the temperature, carrying out iterative calculation to obtain the modal frequency at any temperature. The modal frequency value at any temperature is obtained by arranging a small number of sensors and canying out a small number of tests, so that the influence of the temperature on the modal frequency is quantified, furthermore, the part of environmental influence is eliminated in future damage evaluation of the beam bridge, which allows for a more accurate isamage evaluation rttsult,

A modified version of a MEMS self-test procedure is presented that can be used to detect the amplitude and frequency of an external vibration from an ambient environment. The method implements processing circuitry that correlates an output sense signal, s(t), with a plurality of periodic signal portions and a plurality of shifted periodic signal portions to generate a plurality of correlation values. A frequency associated with the external vibration is determined based on the plurality of correlation values.

A system and method for detecting passage of a pipeline pig, the system and method including a passive impulse detector (10) having a housing (13); a non-intrusive connection (15) of the housing to an exterior wall (17) of a pipeline (P), at least one vibration sensor (11) housed by the housing, and signal processing (23) including at least one band pass filter (27) configured to receive data collected by the vibration sensor, the vibration sensor and band pass filter configured to monitor frequencies in a predetermined range indicating a series of impulses caused by start-and-stop movement of the pipeline pig. The selected frequencies should be those more easily detectable above the baseline (signature or natural resonance) frequency of the section of pipeline being monitored. In some embodiments, the selected frequencies are lower frequencies. No portion of the passive pipeline pig signal intrudes into an interior of the pipeline.

The disclosure provides a method for identifying a modal frequency of a beam bridge by considering influence of environmental temperature. The method includes the following steps: installing a sensor on a newly-built beam bridge without damage, measuring a dynamic response of the beam bridge cinder ambient excitation, recording temperature data, processing by a modal parameter identification method to obtain a modal frequency value at the temperature, and starting from a modal frequency corresponding to the temperature, carrying out iterative calculation to obtain the modal frequency at any temperature. The modal frequency value at any temperature is obtained by arranging a small number of sensors and carrying out a small number of tests, so that the influence of the temperature on the modal frequency is quantified, furthermore, the part of environmental influence is eliminated in future damage evaluation of the beam bridge, which allows for a more accurate damage evaluation result.

The disclosure provides a method for identifying a modal frequency of a beam bridge by considering influence of environmental temperature. The method includes the following steps: installing a sensor on a newly-built beam bridge without damage, measuring a dynamic response of the beam bridge cinder ambient excitation, recording temperature data, processing by a modal parameter identification method to obtain a modal frequency value at the temperature, and starting from a modal frequency corresponding to the temperature, carrying out iterative calculation to obtain the modal frequency at any temperature. The modal frequency value at any temperature is obtained by arranging a small number of sensors and carrying out a small number of tests, so that the influence of the temperature on the modal frequency is quantified, furthermore, the part of environmental influence is eliminated in future damage evaluation of the beam bridge, which allows for a more accurate damage evaluation result.

A method for monitoring vibrations of the winding overhang in a generator (2) comprises the following steps: —detection of vibrations of the winding overhang (15) during the operation of the generator; —transformation of signals of the vibrations into the frequency range; —transformation of multiple individual vibrations from the frequency signals into the modal range; and —determination of deviations of the modal forms and/or individual bar vibrations in relation to a reference response.

A method for monitoring vibrations of the winding overhang in a generator (2) comprises the following steps: —detection of vibrations of the winding overhang (15) during the operation of the generator; —transformation of signals of the vibrations into the frequency range; —transformation of multiple individual vibrations from the frequency signals into the modal range; and —determination of deviations of the modal forms and/or individual bar vibrations in relation to a reference response.

A method for operating a machine plant having a shaft train, including: a) determining the harmonic frequency of a torsional vibration mode of the shaft train and determining mechanical stresses arising during a vibration period of the torsional vibration mode; b) determining a correlation for each torsional vibration mode between a first stress amplitude, at a position of the shaft train that carries risk of stress damage, and a second stress amplitude, at a measurement location of the shaft train, using stresses determined for the respective torsional vibration mode; c) establishing a maximum first stress amplitude for the position; d) establishing a maximum second stress amplitude, corresponding to the maximum first stress amplitude, for the measurement location; e) measuring the stress of the shaft train while rotating; f) determining a stress amplitude at each harmonic frequency; g) emitting a signal when the stress amplitude reaches the maximum second stress amplitude.

A method for operating a machine plant having a shaft train, including: a) determining the harmonic frequency of a torsional vibration mode of the shaft train and determining mechanical stresses arising during a vibration period of the torsional vibration mode; b) determining a correlation for each torsional vibration mode between a first stress amplitude, at a position of the shaft train that carries risk of stress damage, and a second stress amplitude, at a measurement location of the shaft train, using stresses determined for the respective torsional vibration mode; c) establishing a maximum first stress amplitude for the position; d) establishing a maximum second stress amplitude, corresponding to the maximum first stress amplitude, for the measurement location; e) measuring the stress of the shaft train while rotating; f) determining a stress amplitude at each harmonic frequency; g) emitting a signal when the stress amplitude reaches the maximum second stress amplitude.