The paper presents and describes a solution for on-line, in-situ automatic cleaning and calibration of stand alone sensors that measure quantities used in the assessment of rivers and lakes water quality. The system, which was also designed to extract water samples for measurement, includes a set of pumps and electro-valves that are controlled by a microcontroller (PIC17C752) based unit. The control and primary data processing is performed by a LabVIEW Real Time controller (FP-2000) that communicates RS232 with the microcontroller based unit. The advanced data processing is made on a laptop...
In the paper is proposed an original calibration method for microcalorimeter measurements on thermistor power sensors and certain preliminary experiments are illustrated, which are necessary for the effective application of the method. This new method avoids some critical steps in the usual microcalorimeter calibration, saves the time and does not require vectorial measurements for the feeding path sections.
It is shown in the paper that the shape and the contour of the objects can be detected high-precisely using the scattered light. The simulation of the scattered light using the simulation software at first pursues the possibility of the high precise measurement. The possibility of the high-precise measurement is confirmed in the simulation. The simulation results are verified by the experiments next. It is shown that the precise micron meter order measurement is possible using the scattered light from the results of the simulation and the experiment. The method is applied to the inspection...
Any practical oscillator has fluctuations in its amplitude and frequency. These fluctuations represent random amplitude modulation and phase jitter in the time domain. In the frequency domain there is a broadening of the signal frequency spectrum around a nominal frequency. The basic noise is a quantification of the quality of each oscillator and generator, and a measure of the quality of the equipment and of the system in which they are used. These noises determine the external interference immunity of all equipment and the interferences generated in the most frequent applications, in radio...
The paper is focused on instrument current transformer (CT) function during non-standard operating state that is caused by DC transient current component. There is described a way, how to build a numerical model, when CT material parameters are known. The numerical model allows behaviour simulation of the real CT, so it is possible to solve the output current time behaviour if there is defined any transient current waveform at its input terminal. Results enumerated by the numerical model were compared with results measured at the real CT. Comparison between enumerated and measured waveforms...
This paper presents the derivation and effects of a genuine algorithm for identification of circular parametric operators describing performance of periodically time-varying systems, of one input – one output type. The periodic steady state is taken into the consideration, while the period of the change of the system parameters overlaps the period of the changes of input and output signals. Within the domain of discrete time, such operators take the form of a real element matrix. A circular parametric operator may be transformed into the frequency domain. In this version, the quantitative...
Two-part paper presents the synthesis of some author’s works on unified backgrounds of immitance multivariable (nD) measurements of few jointed variables and on the unconventional signal conditioning in four terminal (4T) bridge circuits used for that. In the Part 1 four different circuits for 2D measurements was proposed. Short description of equations and main parameters of the 4R bridge as X type twoport with variable parameters and then as circuit 4T unconventionally supplied by two current sources, named double current bridge (2J) are given and shortly discussed. In the Part 2...
In two parts of this paper is presented the synthesis of some author’s works on unified backgrounds of immitance multivariable (nD) measurements of few jointed variables and on the unconventional signal conditioning in four terminal (4T) bridge circuits used for that. In Part 1 four different circuits for 2D measurements are proposed. Short description of equations and main parameters of the 4R bridge as twoport type X of variable parameters and then as circuit 4T unconventionally supplied by two current sources, named double current bridge (2J) are given and shortly discussed. In Part 2...
The paper presents the probe for measuring high impedance in range of 1 kΩ≤|Zx|≤100 GΩ. The probe can cooperate with gain-phase analysers. The influence of the probe parameters (parasitic capacitance, tolerance of resistors determining amplifier gain) on the accuracy of the determination of modulus and argument of the complex ratio of signals extracted in the probe has been analysed. The results of simulations and measurements have been included, which allow entering corrections in order to increase the accuracy of the impedance measurement.
Accurate dc current transformers (DCCTs) are required for high current precision power supplies- Three basic categories of devices are available: devices which uses Ohms law (V=RI) called current shunts, devices which use Amperes law ( ∫ Hdl =ΣI ), called magnetic current sensors, and devices which uses both, called direct current transformers, DCCT’s The novel DCCT (NDCCT) uses Amperes law, and a reed relay (RR) as magnetic current sensor to detect when the primary and secondary ampere-turns would exactly be equal in magnitude and opposite. RR detects the zero flux condition occurring at...