- Piotr Kędzia and Zbigniew Kosma The influence of Helmholtz and Golay coil homogenity on rectangular plate bending abstract | full text
- Anna Perelomova Self-refraction of impulse and quasi-stationary acoustic beams containing shock fronts in a Newtonian fluid abstract | full text
- Robert Kałaska and Paweł Czarnul Some security features of selected IoT platforms abstract | full text
- Henryk Krawczyk and Paweł Lubomski Bridge of Knowledge: an Internet platform for R2R and R2B transfer of knowledge and promotion of cooperation abstract | full text
- George J. Papadopoulos Tunnelling effects of a Gaussian wave packet impinging on a barrier abstract | full text
hPiotr Kędzia and Zbigniew Kosma The influence of Helmholtz and Golay coil homogenity on rectangular plate bending
The subject of the paper is a rectangular plate. The structure of the plate is symmetrical. The plate is made of a cellular structure of a core and two external faces. There is ferrofluid in each cell of the porous core. The core is made of polyethylene foam and two faces are polyurethane sheets. It is assumed that cells in the core are regular and dense and the faces are thin, therefore, a plate filled in with ferrofluid can be treated as homogeneous. The plate is placed in the magnetic field. The magnetic field is generated by two systems of coils – the Helmholtz coil (HC ) and the Golay coil (GC). The former generates an almost fixed magnetic field in the considered volume (where the plate is placed), and the latter generates a gradient magnetic field. The changing size of each subsystem of magnetic field coils, the distribution and strength of the magnetic field change as well. The magnetic field induces loads in the plate, both perpendicular and in plane. The plate bending function is approximated by the bicubic spline function presented by normalized B-spline functions. The influence of changes in the homogeneity volume and the magnetic field strength (by changing the coil size) on the plate bending is analyzed in the paper. The results of the analysis are presented in tables and figures.
hAnna Perelomova Self-refraction of impulse and quasi-stationary acoustic beams containing shock fronts in a Newtonian fluid
The self-refraction of some beams in a Newtonian fluid is theoretically studied. A single pulse that takes the shape of an isosceles triangle at a transducer and a solitary shock wave are considered as examples. The novelty lies in the consideration of a quasi-stationary shock wave (with positive or negative pressure) and negative triangular pulses. We conclude that waveforms with negative excess pressure undergo self-focusing, in contrast to those with positive excess pressure. The difference in self-refraction of quasi-stationary and impulse beams is revealed by means of numerical modeling.
hRobert Kałaska and Paweł Czarnul Some security features of selected IoT platforms
IoT (Internet of Things) is certainly one of the leading current and future trends for processing in the current distributed world. It is changing our life and society. IoT allows new ubiquitous applications and processing, but, on the other hand, it introduces potentially serious security threats. Nowadays researchers in IoT areas should, without a doubt, consider and focus on security aspects. This paper is aimed at a high-level review of the existing IoT enabling standalone middleware solutions and frameworks in terms of potential application areas, architecture and components, communication APIs as well as support for key security features including access control, support against attacks on service, device authorization and data filtering. On the one hand, it allows the developer to choose the middleware best matching their needs. On the other hand, it can serve as a starting point for further research on middleware security features based on the provid ed security related open areas and challenges.
hHenryk Krawczyk and Paweł Lubomski Bridge of Knowledge: an Internet platform for R2R and R2B transfer of knowledge and promotion of cooperation
Currently, the European Commission puts emphasis on supporting collaboration between universities and business. There are many possible ways to create a strong relationship between both these parties. Positive results of such cooperation lead to increased competitiveness of the global market and, in consequence, bring significant growth of innovation. The cooperation between research-to-research (R2R) and research-to-business (R2B) is analysed. The paper shows how the IT technology can be used to support and stimulate it. In our University we proposed a two-step strategy. Firstly, we tried to improve collaboration among scientists in order to develop R2R activities. Secondly, we focused on R2B projects that stimulate promising scientists to take part in various innovative activities carried out in cooperation with the industry representatives. Based on some well-known good practices a special Internet platform was designed and implemented to support such a strategy. Its name is the “Bridge of Knowledge”. The platform architecture, its functionality and some other aspects of the development process are described. The platform was developed and introduced at the Gdańsk University of Technology. It has been available online for nearly 2 years now and it has been attracting increasing numbers of new visitors and returning users. Several use cases of cooperation between R2R and R2B were analysed and described with the use of advanced analytic tools and on the basis of the organisation's resources. The idea of the Bridge of Knowledge platform is to gather and share resources not only from one university. The architecture of the platform focuses on a wide and easy interoperability. Other universities can share their resources without any additional cost.
hGeorge J. Papadopoulos Tunnelling effects of a Gaussian wave packet impinging on a barrier
A general procedure based on momentum-like quantity provides the reflection and transmission amplitudes for a given barrier sandwiched by semiconductor reservoirs is presented. Furthermore, the evolution of the wave function stemming from an initial Gaussian wave packet located on the left hand side of the barrier with ignorable barrier overlap is obtained. The evolving wave function enables obtaining the associated probability and current densities space and time-wise. As application, the case of smooth double barrier is considered. The numerical results exhibit similar picture as obtained via propagator in the limited case of square barrier, e.g. repeated current density reversal at the barrier entrance, while being unidirectional at the exit. Presently, the treatment takes account of any barrier, inclusive of applied voltage. The basic quantity required is the value of the momentum-like quantity at the barrier entrance, which is obtained solving a Riccati equation governing the quantity, in question, whose value is known at the barrier exit in terms of the carrier energy and applied bias.