The paper investigates the problem of improving driveability of alpine skis. That properties
depend largely on the vibration behavior of a ski under different snow conditions. There is a broad
range of methods to deal with vibration damping, both active and passive, that have been
described in the literature. In this paper the passive approaches were taken into consideration. It is
due to the specific nature of the sport where use of external sources of energy may be impractical.
Passive shunt damping system has been designed for a commercially available model of an
alpine ski. The performance of the designed system has been evaluated on a numerical model of
the ski. Piezoelectric patches have been included in the model by means of a generalized
impedance that complies both the mechanical properties and shunted circuit electrical properties.
The fraction of strain energy stored in a piezoelectric element at particular vibration modes were
used to evaluate the maximum damping coefficient for first three resonant modes that have the
largest influence on the ski properties. The damping system is based on piezoelectric patches that
can be easily embedded in the laminated structure of a ski.
Extremal control is an optimization performed by experimenting with optimised device directly
during operation. On our department we deal with the extremal control of torsional oscillating
mechanical systems by means of pneumatic flexible shaft couplings. The torsional stiffness of
these couplings and so the natural frequencies of torsional systems can be changed by adjusting the
air pressure in their pneumatic flexible elements. The goal of this optimisation is to minimize the
value of torsional vibration by changing the pressure of gaseous medium in the used pneumatic
flexible shaft coupling. The goal of this article is to confirm the possibility of the use of extremal
control in a laboratory torsional oscillating mechanical system built on our department.
In this paper a long term observation of the technical state of building positioned in the area of
coal mine exploitation is presented. The investigated structure was induced to vibrate using impact
excitation. The points of excitation were located on two different pillars supporting the building. In
order to extract dynamic parameters of the structure, experimental modal analysis was applied.
The parameters of vibration resulting from this excitation were measured by a scanning laser
vibrometer. To introduce and compare classical and operational modal analysis, piezoelectric
accelerometers were additionally utilized. Moreover, to investigate and explain the changes in the
state of the building a finite element model (FE) was built. The analysed building is situated on the
terrain of underground coal mine exploitation so the aim of the research was not only to observe
the state of the building, but also to analyse possible changes during the process of excavation and
after its completion. The building was observed from 2009 to 2012. Identification of the state of
building using a laser scanning vibrometer proved feasible and relevant from a practical point of
System automatycznego dozorowania ADS – B jest nisko kosztowym systemem dozorowania,
który zapewnia okresowe transmitowanie parametrów statku powietrznego (identyfikacja,
położenie) poprzez tryb transmisji łącza danych. Informacja z ADS – B jest nadawana bez
względu na to, który z użytkowników będzie ją odbierał (inny statek powietrzny, kontroler ruchu
lotniczego) i bez oczekiwania na odpowiedź tego użytkownika. Niemniej jednak, wymagane jest,
aby informacja była udostępniana na obszarach objętych dozorowaniem przez służby kontroli
ruchu lotniczego. Każdy użytkownik, zarówno w przestrzeni powietrznej, jak i w stacji naziemnej
może wybrać sposób użytkowania systemu: otrzymywanie, przetwarzanie lub wyświetlanie
Increasing cost of rotorcraft maintenance forces transport companies to utilize their rotorcraft
fleet to the fullest. This means that the most successful rotorcraft production company is the one
that can provide rotorcraft that can operate in wider range of weather conditions than competition.
Air transport authorities define requirements for both rotorcraft performance during flight in icing
conditions and reliability of ice accretion protection systems. At the same time production
company management requires that production, and development costs are as low as possible.
This paper will focus on problems of meeting requirements of rotorcraft ice protection systems
reliability using various types of reliability analyses that will help keep the system as simple and
inexpensive as possible and are required in certification process of ice protection system.
The paper concerns classification of technical condition state of rolling bearings. A
methodology of optimization of a k-NN classifier with regard to selection of the symptom
observation space has been proposed. The symptoms carrying the most information allowing
identification of a class of technical condition were selected. The applied methodology enabled to
develop a classifier which in the set of available data achieved the efficiency of 97.5%. In the set
of considered symptoms the r.m.s. and peak values of vibration acceleration in the broad
frequency band and the energy of acoustic emission pulses turned out to be the best for
identification of arising fracture of a bearing outer ring.
The article presents the method for the support of diagnostic processes with the use of an
original computer system in which augmented reality is applied. The proposed solution constitutes
a significant step towards improving actions directed at the assessment of the technical condition
of complex technical devices. The research problem presented in the article was defined through
the determination of the scope of diagnostic tasks which the personnel may find difficult in certain
technical conditions. The research method consisted in the selection of a technology facilitating
effective execution of diagnostics of complex technical devices. In the developed solution
diagnostic processes are executed via the visual presentation of the following: the location of the
components of the device, the diagnostic tasks, the descriptive hints, the measurement values, the
location of the measurement points, and the 3D models of the components.
The paper presents comparison of damping characteristics determined for new hydraulic shock
absorbers. The damping characteristics were determined on indicator test stand for six new front
shock absorbers of the same type. On the basis of these results was made the statistical analysis
as well as the comparison of the received characteristics.
During the development of the aircraft structure, test flights are indispensible. In some
experiments additional sensors are mounted, which often leads to certain technical problem. In
particular, changes of the structure are necessary and additional costs are generated. Therefore,
advanced measurement methods enabling an analysis of several parameters without adding special
sensors are developed. One of the projects focused on problems of measurement during the flight
is the AIM2 project in the frames of FP7. During research mobile optical measurement systems
and application rules are developed As described in references [1, 2], the AIM project - Advanced
In-flight Measurement Techniques – focused on the application of modern optical measurement
techniques in industrial wind tunnels for the purpose of flight testing. Possibilities to measure wing
and rotor deformation, surface pressure distribution, heat distribution and flow velocity fields in a
non-intrusive way and with a minimal sensor setup were presented in the AIM project. Also, the
most important challenges connected with industrial implementation of methods demonstrated in
the AIM project were taken into consideration. The research is being continued in AIM² project.
AIM2 aims at the development of measurement methods for easy and typical applications to inflight
testing with industrial requirements.
In order to test the optical measurement methods, additional flight data are required. The data
required are angular rates in the body frame, Euler angles, accelerations, IAS, TAS, altitude. This
article describes a system which is used in the project for additional data measurements. The
whole system will be mounted on the board of the PW-6 glider.
The diagnostic and operating criteria as well as the environmental protection impose very
diversified requirements on the parameters of work of car engine oils in the area of lubricity and
rheological properties. The aim of the work was the estimation of resistance to wear of the
elements lubricated with these oils working at sliding friction as well as the estimation of
rheological parameters of the oils in the reference temperature and in sub-zero and low
temperatures at controlled shear stress. The tested materials included mineral engine oils,
semisynthetic and synthetic ones that belong to different viscosity classes. Wear defects were
determined with the use of the four-ball testing machine and also the characteristics of viscosity
were described with the help of the rotational rheometer. On the basis of the results of the tests, in
accordance with the elaborated method it is possible to compare oils designed for application and,
at the same time, diagnose the way in which they will secure motive nods in the conditions of
The article presents a method and results of the implemented measurements of loads of a single carrying
idler set on a belt conveyor under working conditions. Currently, identification of the quantity and
flow stream of material on the conveyor\'s belt in mining conditions takes place by means of roller
weights. These are devices ensuring identification of temporary efficiency, however, they do not allow
precise definition of the scope of real forces to which a single idler is subjected to in the set. Such information
can be obtained using a strain gauge measurement method prepared in the Mining Institute of the
Wrocław University of Technology. At this point it should be remembered that nothing else but load is a
key input parameter in any analyses and design calculations of idlers. The obtained measurement results
of loads of carrying idlers and the conducted analyses of performed experimental works find practical
application in the process of optimizing construction solutions of idlers - both with regard to the strength
and operating requirements. They may be used to estimate a level of durability of idlers and are a valuable
source of information when determining the actual level of their power consumption. The selected
examples of such applications have been included in this paper.