Sensitive pressure sensor with nitride membrane and optoelectronic read-out system is described. Measured pressure is transformed into thick layer nitride membrane deflection. Nitride membrane serves as a mirror for laser beam and can move reflected laser mark. Mark’s position is sensed using position sensing device – fotolateral diode. Diode double current signal is amplified and conditioned digitally by ADuC 812 microcomputer. This one chip microcomputer provides an IEEE 1451.2 interface.

The convenience to analyze ultrasound signals with a digital trasform is compared with the application of an analogic module extractor. The accuracy the analogical apparatus can reach, is compatible with the optimal input that needs an improved maximum likelihood analysis. The computing heaviness is relieved by the possibility to preestimate the echoes parameters and by the elimination, considering time occurrence, of reflected echoes. The parallel adapting of the recursive algorithm to a hardware parallel structure is discussed to make possible the real time application.

In this paper, we present a position sensor based on the magnetostrictive delay line principle. The sensor is accompanied by its electronic circuitry and packaging. We present and analyze the sensor principle, electronics, calibration procedure as well as its evaluation with respect to the state of the art, showing its advantages and applications.

This work provides a detection method for faults in the operation of rotating machines based on a change of system vibration standard and in the operation status diagnosis by fuzzy logic. These changes are analyzed and used as parameters for predicting incipient faults, as well as their evolution in operation condition allowing predictive maintenance tasks. A mechanic structure (developed to insert the faults) called Rotating System (see Fig 1) has been used. The data acquisition of structure vibration has been made by a biaxial solid state accelerometer in a low-power chip. The outputs are directly measured by a microcontroller-based system without needing an A/D converter. The acquisition system is composed by two subsystems: a personal computer and a microcontroller-based front-end (Microchip PIC16C73A). The acquired data (stored in *.dat files) are computed and analyzed in frequency domain with a signal processing tool (called SPTOOL) of the Matlab5 package. The faults analyzed in this work are due to the unbalancing of axle_wheel by insertion of unbalanced elements. The relation of mass between the wheel and the smallest unbalanced element is 1 : 10,000. The fuzzy system was calibrated to detect and diagnose the normal, incipient fault, maintenance, and danger conditions of the Rotating System.

The article describes results of an interlaboratory comparison of instrument current transformers performed in the Czech Republic. An operating instrument current transformer with ratios 400 A/5 A and 800 A/5 A has been used by this comparison. A common instrument transformer has a big dependence of errors on burden and its phase displacement. This dependence is also illustrated. The various results are compared and determined their differences for single laboratories.