Mateusz Gęca

Fuels should behave appropriately in all sections of the engine system: the engine, fuel delivery system, and tank. Fuel quality can be linked to the following three crucial areas: performance, fitness for current use, and stability. Classical methods of diesel fuel examination mostly rely on the absolute value measurement of one specific parameter while stabilizing outside conditions. In contrast, multiparametric methods depend on simultaneously measuring a set of parameters. Therefore, multiparametric methods open the possibility of intriguing new examinations and classifications of diesel fuel quality while raising specific issues relating to the instrumentation and construction of sensing devices. This paper presents a review, based on the published literature and the authors’ research, of the current state-of-the-art multiparametric methods for rapid diesel fuel quality classification and related instrumentation, systematizing the various types of methods from the point of view of the principles of their operation. The main conclusion is that different measuring procedures use similar methods of data processing. Moreover, the heavy, costly, and complex devices that enable standard examinations can be converted to simpler devices in the future, whose cost of use is significantly lower. However, to achieve this, progress in electronic devices is required.

Diesel fuel stability can be considered from many points of view, of which the two considered most important are stability in contact with the environment and internal stability. Fuel stability in touch with the environment is often defined as oxidation stability, of which measurement procedures are well developed. The presented paper shows that fuel’s internal stability can also be important. The internal stability of diesel fuel with the local use of thermal and ultraviolet radiation (UV) as degradation factors and fluorescence signals as a probe is presented in this paper. We show that the internal degradation of fuel with temperature use differs from that with UV and simultaneous both factors use. Our study shows that using temperature as a degradation factor introduces significant fluorescence fading. Moreover, the fluorescence signal restores significantly later than the sample stabilizes at room temperature. The novelty proposed based on examination is hybrid degradation and an examination cycle that enables the simultaneous use of degradation factors and fluorescence reading. For this purpose, a dedicated measurement setup of signal control and processing was constructed and programmed. The measurement procedure of the data series for specific wavelength enables calculation of signal shifts that allow the internal stability classification of diesel fuel samples in less than 30 min with the cost of a single disposable capillary probe and one polymer plug. Premium and regular fuel examination results show that internal fuel stability can be related to polycyclic aromatic hydrocarbons (PAH) concentrations and can be modified with dedicated additives.

In this paper, the technology for fabricating NiFe/Cu/NiFe layered structures by magnetron sputtering is presented. Two series of samples were fabricated on a glass substrate with a layered structure, where the individual layers were 30 nm NiFe, 5 nm Cu, and finally NiFe with a thickness of 30 nm. The series differed in the type of technology mask used. A constant magnetic field was applied to the substrate during the sputtering of the ferromagnetic layers. Measurements of the DC resistance of the obtained structures in the constant magnetic field of neodymium magnet packs with a constant magnetic field of about 0.5 T magnetic induction have been carried out. Comparison of the two series allows us to conclude the greater validity of using masks in the form of Kapton tape. The obtained results seem to confirm the occurrence of phenomena referred to as the giant magnetoresistance effect.

This paper describes the basic information about the phenomenon of giant magnetoresistance as well as the structures exhibiting in which this phenomenon is observable. The technological sequence of NiFe/Cu/NiFe thin structures fabricated by magnetron sputtering is presented. The two series of structures presented differ in the thickness of the non-magnetic copper layer used being 5 nm and at 2,5nm. Measurements of the DC resistance of the structures of both series in a constant magnetic field of 0.5 T were performed. Comparison of the obtained results allows us to conclude that the changes of the structure resistance under the giant magnetoresistance phenomenon are larger for smaller thickness of the copper layer.

The paper presents the technology for obtaining NiFe/Ti/NiFe layer structures in MEMS technology using magnetron purge with the assumption of being used as semi-magnetic sensors. A series of samples was made on a glass substrate with a sandwich structure, where the individual layers were 100 nm NiFe, 10 nm Ti and on top again NiFe with a thickness of 100 nm. Measurements of DC resistance of the obtained structures in a constant magnetic field, which was produced by neodymium magnets and an electromagnet, were carried out. The obtained results confirm the occurrence of phenomena known as the magnetoresistance effect. The influence of the spatial arrangement of structures relative to the constant magnetic field vector was checked and proved.