The AC and DC dielectric properties of hydrofluoroethers (HFE) [C₃F₇OCH₃] and fluorinated ketone (FK) [C₂F₅C(O)CF(CF₃)₂] have been characterised by dielectric spectroscopy and DC conductivity at different temperatures. Results show that DC conductivity and imaginary permittivity of both fluids are positively correlated with increasing temperature. However, the real permittivity decreases with increasing temperature. The breakdown voltages of HFE and FK at 295 K are ∼10 kV mm⁻¹. Reducing temperature is an effective method to increase the breakdown voltage of the FK coolant, but the breakdown voltage of HFE is less temperature dependent. Finally, as expected repeated breakdown had no significant effect on the AC dielectric strength of both liquids.

The microbial inactivation and specific energy of a pulsed electric field treatment system are dependent on the electric field distribution and treatment time since they have opposite behaviour in relation to these parameters, featuring a problem of multi-objective optimisation. This study proposes a computational methodology capable of providing Pareto optimal solutions for these two objectives, using a coupled electrical-thermal model, solved by COMSOL, which has been integrated to a multi-objective algorithm NSGA-II implemented in MatLab. The simulations were run for a computational design of experiment with the following variables: applied voltage, treatment time and the internal electrode radius (three levels for each one). In the post-processing analysis, the Pareto curves were plotted for two typical microorganisms of grape juice: E. coli and S. aureus, providing a set of solutions in terms of the log of the survival rate versus the specific energy. The methodology enables the decision maker to select the best solution from the Pareto curves as a function of a required microbial inactivation and energy features.

An axial magnetic field (AMF) plays an important role in the process of vacuum arc stabilisation during the current breaking process in the vacuum circuit breakers (VCBs) of the AMF type. To minimise the contacts erosion special attention should be paid to reach a possibly high value of the AMF density (between contact plates), especially in the outer electrode region. Various contact geometries are patented all over the world to improve the AMF distribution. Nevertheless, there is an issue which is not raised in the literature as yet. It is the mutual orientation (rotation) of the moving and fixed contacts. This orientation can have an influence on the AMF distribution. The above problem is analysed here numerically using Maxwell (ANSYS) software package based on the finite element method. The own (patented) contact design is considered in the analysis mentioned. However, the beneficial influence of AMF on the arc behaviour is well known for VCB designers, the explanation of this phenomenon is described (in the literature) rather seldom and very cursorily. Therefore, a simplified model accounting for the role of AMF in vacuum arc diffusion is shortly presented at the beginning of this study.

This research work presents the design of the electronics modules of Adam's Hand, a transradial myoelectric prosthesis based on an innovative mechanism which can actuate five three-phalanges fingers (15 degrees of freedom) with just one motor, instead of the five/six motors conventionally used in other prosthetic devices; moreover, the prosthesis uses two servomotors to actuate the wrist movements. Adam's Hand fingertips are provided with temperature and pressure sensors, while the user myoelectric signals are acquired wirelessly by means of the Myo armband, a wearable device provided with eight electromyography electrodes, a nine-axis inertial measurement unit, and a transmission module. These data are received through an HM-11 BLE module, connected to Adam's Hand custom PCB, which features an Arduino Micro board. This board processes all the data and drives the actuators by means of properly chosen drivers. A Raspberry Pi 3 board manages a touchscreen display – which can be used to visualise the gathered data – and sends them to a dedicate cloud platform, so that the orthopaedic technicians who take care of Adam's Hand users can monitor them in real time, thus improving their recovery during the rehabilitation period.

To solve the complexity of the conventional time-domain reflectometry method for locating minor cable ageing degradation, a frequency domain-based method for locating cable ageing degradation based on propagation coefficient spectrum is proposed in this study. First, the change pattern of cable input impedance spectrum in frequency-domain reflectometry is analysed to reveal the relationship between input impedance spectrum and propagation coefficient, and thus finds out the working mechanism of ageing degradation on propagation coefficient spectrum. Then, in the experiment, a vector network analyser is used to measure propagation coefficient spectrum and the inverse discrete Fourier transform is applied to locate cable ageing degradation. Finally, kurtosis analysis is performed on locating curves of different bandwidth and the upper limit of frequency of the testing signal is decided. Within a certain limit, the method proposed in this study can locate degradation with higher accuracy and resolution than several time/frequency-domain based methods currently adopted.