Power distribution lines are a major source of interference in ECG recordings obtained with surface electrodes. Displacement currents coupled to electrodes, their leads and directly into the body, and stray capacitance in power supply transformers, result into differential-mode, common-mode and isolation-mode interference. Shielding electrode leads reduces displacement currents coupled to them. Amplifiers with high common-mode and isolation-mode rejection ratio reduce common-mode and isolation-mode interference, but interference coupled in differential mode cannot be reduced by shielding neither by amplifier design. We propose the use of a grounded electrode close to each recording electrode instead of the customary "right-leg" ground electrode, to reduce differential-mode interference. We provide a qualitative model to explain that interference reduction, and experimental evidence to show its effectiveness even for non-isolated recording systems in the presence of strong power-line interference.

The use of high-tech plastics in the field of mechanical engineering is increasing dramatically. The time-dependent change of strain ε(t) during constant load (viscoelasticity, creeping) is a fundamental property of plastics and exact knowledge of these properties is required for the design of plastic parts. A novel high-resolution materials testing device is presented in this paper. It offers reaction-free interferometric measurement of the viscoelastic behaviour of plastics at a constant bending load. The resolution of the deflection is 1 nm.
Therefore, unlike the three point bending test described in the ISO 899-2:2003 standard, the device is suitable for the measurement of viscoelasticity ε(t) at very small strain values (ε_max < 0.1 %) and after a very short loading time (t < 1 d).
A detailed description of the device and the parameters is shown as well as measurements of the time-dependent strain ε(t) of a high-tech plastic. Very good reproducibility of the measurements was achieved, which makes the device very suitable for measuring viscoelastic behaviour.

The positional deviation (difference between the actual and target position) belongs to the important criteria that describe the performance of numerically controlled axes. The procedure for determination of such deviation is described in the international standard ISO 230- 2:1997. This standard provides calculation of the positional deviation only in several discrete (measuring) points. Moreover it does not consider effects of the measuring instrument on the obtained results. The new methodology is adopted and it is enables estimation of the positional deviation in any point of the axis travel, together with the uncertainty of such estimate. Obtained results can be incorporated into a control system in the form of corrections enhancing positioning possibilities of individual axes.
The paper introduces procedures that were verified by measurements for one linear axis. The more complicated situation occurs for testing the positioning accuracy in a plane or in a space. Paper also talks about possibilities of using such a measurement in process of controlling for compensation. Such compensation can bring great improvement in positional accuracy of machine tools.

We present results of experiments for characterising complex (i.e., multiple-scattering and time-varying) environments for propagation of microwaves. Parameters of the distortion of the received signals are analyzed using statistical and stochastic methods.

The paper presents the proposal of a new mathematical tool for LabVIEW environment – the Large Number Library. After the short introduction describing the security issue in the Distributed Measurement-Control Systems (DMCS), the most popular asymmetric encryption algorithms (public-key encryption algorithms) are described in order to demonstrate the need for developing such a library. The LN library was implemented in two variants: the native LabVIEW code (G language) and using external software modules (DLLs). The algorithms implemented in both alternatives have been developed basing on the Number Theory Library (NTL) – Victor Shoup's open source library. The results of accuracy and efficiency tests for several functions implemented in both variants are shown. The developed LN library will allow for the creation of the advanced cryptographic libraries dedicated to the LabVIEW environment, enabling the development of secure communication channels in DMCS and information security of DMCS networks.