Number Of Transient Signals Research Articles

Open pit slope deformation monitoring by fiber Bragg grating sensors

With microstrain resolution and the capability to sample at rates of 2000 Hz or higher, fiber Bragg grating (FBG) strain sensor offers exciting new possibilities for in situ deformation monitoring induced by blasting load in an open pit slope. Here, we are developing a new technology for measuring deformation in real time on the microstrain in an open pit slope during the blasting. A fiber optically instrumented rock mass strain sensor measured strain at 100-cm intervals along a two anchor rock bolt grouted in the slope intact rock mass. In field testing, a number of transient signals have been observed, which in some cases were large enough to trigger rapid sampling. The combination of short- and long-term observation offers new insight into the slope stability and blasting cumulative effects. Therefore, FBG sensors are a useful tool for measuring in situ strain in intact rock masses.

The Impedance Calculation Methods Using Damped Sinusoidal Signal

There are large number of transient signals will be produced when the operation mode is changed. And the frequency of the transient signals distributed in wide range. The most of them are damped and oscillated. The impedance is a popular feature in power system, and it has been widely used in relay protection and fault location. So the impedance calculation based on the damped sinusoidal signal have been the important way to diagnosis the fault, locate the fault and so on. But the methods used now are based on the fundamental impedance calculation theory, lacking theoretical basis. In fact, the traditional methods for fundamental signal calculation are not appropriate for the quantitative analysis of damped sinusoidal signal. The paper analyzed the impedance calculation based on damped sinusoidal signal, combined the features of damped sinusoidal signals and the traditional impedance calculation method. The two typical signal analysis methods for damped sinusoidal signal extraction are used to calculate the accurate impedance based on the different extraction results. And the analysis laid a foundation for the impedance calculation using damped sinusoidal signals.

Rockslide deformation monitoring with fiber optic strain sensors

Abstract. With micro-strain resolution and the capability to sample at rates of 100 Hz and higher, fiber optic (FO) strain sensors offer exciting new possibilities for in-situ landslide monitoring. Here we describe a new FO monitoring system based on long-gauge fiber Bragg grating sensors installed at the Randa Rockslide Laboratory in southern Switzerland. The new FO monitoring system can detect sub-micrometer scale deformations in both triggered-dynamic and continuous measurements. Two types of sensors have been installed: (1) fully embedded borehole sensors and (2) surface extensometers. Dynamic measurements are triggered by sensor deformation and recorded at 100 Hz, while continuous data are logged every 5 min. Deformation time series for all sensors show displacements consistent with previous monitoring. Accelerated shortening following installation of the borehole sensors is likely related to long-term shrinkage of the grout. A number of transient signals have been observed, which in some cases were large enough to trigger rapid sampling. The combination of short- and long-term observation offers new insight into the deformation process. Accelerated surface crack opening in spring is shown to have a diurnal trend, which we attribute to the effect of snowmelt seeping into the crack void space and freezing at night to generate pressure on the crack walls. Controlled-source tests investigated the sensor response to dynamic inputs, which compared an independent measure of ground motion against the strain measured across a surface crack. Low frequency signals were comparable but the FO record suffered from aliasing, where undersampling of higher frequency signals generated spectral peaks not related to ground motion.

Optimizing the multielement analysis capabilities of an ICP quadrupole mass spectrometer using electrothermal vaporization sample introduction.

A mathematical solution and an experimental procedure are described for calculating the maximum number of transient signals, such as those obtained using ETV sample introduction into an ICPMS, that can be monitored by a scanning spectrometer, such as a quadrupole mass analyzer. The total number of masses that can be monitored per ETV firing is shown to be dependent on the values chosen for data collection (i.e., scan time and dwell time) and the necessary limits of detection required by the method. The theory shows the effect that statistical noise, peak shapes, and inconsistent peak appearance times have on the overall variance calculated for the sample concentration based on total counts or "peak area". Also included in the variance calculation is the contribution made by the autosampler as an example of one type of error that is not associated with the data collection parameters. The theory is validated by two experiments where 21 and 68 transient signals are monitored per ETV firing; and as predicted, a 10 ppb sample is accurately quantified with precision better than 9% in both cases.