9762 papers found
A new concept of distributed IEEE-488 measuring systems using Java architecture is proposed. A connection of external modules (standard library for National Instruments IEEE-488.2 interface board) to source code in Java is described. Next, an example of the system, that uses a communication based on sockets for remote controlling of instruments, also via Internet, is presented.
System complexity and long time of monitoring of signals in radiomonitoring systems increases fault appearance probability which may have influence on the measurement results. Hence the necessity of built-in self testing algorithms to increase monitoring credibility of radio and TV transmitters. In the paper a testing method based on level measurements of known electromagnetic signals sent near the receiver antenna is presented.
The present work concerns magnetic circuits which are built of laminated soft magnetic materials, e.g. cores of transformers or of rotating machines. Such systems tend to show very complex local distributions of the magnetic field vector H , the induction vector B and the energy loss P . For simultaneous measurements of all these local quantities, we designed a hand-held sensor which can be arranged on the surface and - taking advantage from small sensor thickness - also between the core sheets. All data are displayed instantaneously on the computer screen. The measuring method is based on...
This paper concerns effects of mechanical stress on soft magnetic silicon iron sheets subject to rotational magnetization (RM). RM is typical for armatures of rotating machines and for T-joint regions of transformer cores. In both cases, distinct mechanical stress may arise, e.g., from temperature changes or from clamping. Simulation of such magneto-mechanical conditions on a specifically designed test apparatus shows that tensile (or compressive) stress of several MPa intensity yields distinct effects on all three permeability, energy losses and magnetostriction.
The paper presents a new concept of virtual electronic scales (VES) conceived as a PC peripheral. The traditional approach, “specific scales for specific application”, has dominated the development and production of both mechanical and state-of-the-art electronic scales. The main aim of this paper is to promote a PCbased approach – electronic weight scales as a virtual instruments. The paper offers a detailed presentation of originally developed hardware and software structures of VES called Soft Scales, based on strain-gauge load cells, of 2... 200 kg measurement range, accuracy class III,...
The calibration system for vector DC magnetometers of Nurmijarvi Geophysical Observatory (Finland) is described. It is based on a three axes reference coil system and Observatory reference magnetometer. It is shown experimentally that the system allows to determine calibrated magnetometer parameters with an error about 0.02%. One important error source -influence of noncollinearity of reference and calibrated magnetometer axes - is analyzed and value of this error is estimated. Also additional possibilities of the Observatory infrastructure are described: determination of temperature errors...
The computer-controlled system for low-frequency noise measurements has been presented. All major functions for adequate polarisation of a device under test are programmable providing complete flexibility and automation for biasing. The inherent noise parameters of the main modules are enclosed. The system enables to measure input-output noise relations for BJTs, JFETs, MOSFETs, MESFETs, HEMTs, and, in general, also other two-ports.
Abstract: The article deals with measurements of signals emitted by a radiocommunication transmitter during transient states. It contains a brief description of measures and measurement methods traditionally used for testing transients. The methods for transmitter behaviour evaluation based on wavelet transform are presented and their features are discussed. The paper contains results of computer simulations as well as measurements of an exemplary transmitter.
A low-cost switch for ac-dc transfer is presented in this paper. The switch performs fast switching of the input of the thermal voltage converter (TVC) between AC and DC calibrator outputs. It can be controlled through the GPIB bus, manually and through the serial RS-232 interface. Both 4-wire and 2-wire connection between the TVC and the calibrators is possible. The switch provides very fast switching. The dead time of the switch is less than 5 ms. The switch is well protected against relay and power failures.
This paper deals with Digital Signal Processing techniques of noisy current signals from electric motors in order to form reasonably reliable energy estimates applied to the plant control of rubber mixing room processes. The algorithms proposed are characterized with a good result rate. They are implemented in practice and can be successfully used for technological experiments of new products.