Bulletin of the Polish Academy of Sciences: Technical Sciences

Swing-up control of a single pendulum from the pendant to the upright position is firstly surveyed. The control laws are comparatively studied based on swing-up time from a given initial state to the upright position. The State Dependent Riccati Equation is found effective for designing the swing-up control law under saturating control input. The control law is extended to a linear combination of sine function of the angle and the angular velocity, and a variable structure control with a sliding mode given by the linear combination. Making the swing-up time correspond to a colour, which is similar to the Fractal analysis, colour maps of the swing-up time for given control parameters and initial conditions yield interesting Fractal-like figures.

Shape memory alloys are characterised by interesting properties, i.e. shape memory effect and pseudoelasticity, which enable their increasing application. Thermomechanical aspects of martensitic and reverse transformations in TiNi shape memory alloy subjected to tension tests were investigated. The stress-strain characteristics obtained during the tests were completed by the temperature characteristics. The temperature changes were calculated on the basis of thermograms determined by an infrared camera. Taking advantages from the infrared technique, the temperature distributions on the specimen’s surface were found. Heterogeneous temperature distributions, related to the nucleation and development of the new martensite phase, were registered and analysed. A significant temperature increase, up to 30 K, was registered during the martensitic transformation. The similar effects of the heterogeneous temperature distribution were observed during unloading, while the reverse transformation, martensite into austenite took place, accompanied by significant temperature decrease.

This paper describes a design process of HALE PW-114 sensor-craft, developed for high altitude (20 km) long endurance (40 h) surveillance missions. Designed as a blended wing (BW) configuration, to be made of metal and composite materials. Wing control surfaces provide longitudinal balance. Fin in the rear fuselage section together with wingtips provide directional stability. Airplane is equipped with retractable landing gear with controlled front leg that allows operations from conventional airfields. According to the initial requirements it is twin engine configuration, typical payload consists of electro-optical/infra-red FLIR, big SAR (synthetic aperture radar) and SATCOM antenna required for the longest range. Tailless architecture was based on both Horten and Northrop design experience. Global Hawk was considered as a reference point – it was assumed that BW design has to possess efficiency, relative payload and other characteristics at least the same or even better than that of Global Hawk. FLIR, SAR and SATCOM containers were optimised for best visibility. All payload systems are put into separate modular containers of easy access and quickly to exchange, so this architecture can be consider as a „modular”. An optimisation process started immediately when the so-called “zero configuration”, called PW-111 was ready. It was designed in the canard configuration. A canard was abandoned in HALE PW-113. Instead, new, larger outer wing was designed with smaller taper ratio. New configuration analysis revealed satisfactory longitudinal stability. Calculations suggested better lateral qualities for negative dihedral. These modifications, leading to aerodynamic improvement, gave HALE PW-114 as a result. The design process was an interdisciplinary approach, and included a selection of thick laminar wing section, aerodynamic optimisation of swept wing, stability analysis, weight balance, structural and flutter analysis, many on-board redundant systems, reliability and maintability analysis, safety improvement, cost and performance optimisation. Presented paper focuses mainly on aerodynamics, wing design, longitudinal control and safety issues. This activity is supported by European Union within V FR, in the area Aeronautics and Space.

The considerations presented in the paper relate to one of the most intriguing phenomena, which is the development of oil whirls and oil whips in rotors with journal bearings. This effect is sometimes referred to as flutter, as its origin is in some relation to self-exciting vibrations of the system. Despite the fact that the flutter has been an object of investigation in numerous research centres all over the world, its nature has not been sufficiently recognized yet. The present paper delivers a description of particular phases of development of the hydrodynamic instability and proposes diagnostic determinants for this state. The object of investigations also included bearings with hybrid lubrication and siphon pockets in the oil gaps. The answer has been received to the question whether the self-exciting vibrations in rotating machines can be avoided, or reduced by means of additional oil supply having the form of siphon oil.

The aim of this paper is to study the applicability of the theory of micropolar fluids to modelling and calculating flows in microchannels depending on the geometrical dimension of the flow field. First, it will be shown that if the characteristic linear dimension of the flow becomes appropriately large, the equations describing the micropolar fluid flow can be transformed into Navier-Stokes equations. Next, Poiseuille flows in a microchannel is studied in detail. In particular, the maximal cross-sectional size of the channel for which the micropolar effects of the fluid flow become important will be established. The experimentally determined values of rheological constants of the fluid have been used in calculations.

The issue of maximizing penetration depth with concurrent retaining or enhancement of image resolution constitutes one of the time invariant challenges in ultrasound imaging. Concerns about potential and undesirable side effects set limits on the possibility of overcoming the frequency dependent attenuation effects by increasing peak acoustic amplitudes of the waves probing the tissue. To overcome this limitation a pulse compression technique employing 16 bits Complementary Golay Sequences (CGS) Code was implemented at 4 MHz. In comparison with other, earlier proposed, coded excitation schemes, such as chirp, pseudo-random chirp and Barker codes, the CGS allowed virtually side lobe free operation. Experimental data indicate that the quality — resolution, signal penetration and contrast dynamics — of CGS images is better than the one obtain for standard ultrasonography using short burst excitation.

Resonance assignment remains one of the hardest stages in RNA tertiary structure determination with the use of Nuclear Magnetic Resonance spectroscopy. We propose an evolutionary algorithm being a tool for an automatization of the procedure. NOE pathway, which determines the assignments, is constructed during an analysis of possible connections between resonances within aromatic and anomeric region of 2D-NOESY spectra resulting from appropriate NMR experiments. Computational tests demonstrate the performance of the evolutionary algorithm as compared with the exact branch-and-cut procedure applied for the experimental and simulated spectral data for RNA molecules.

DNA sequencing remains one of the most important problems in molecular and computational biology. One of the methods used for this purpose is sequencing by hybridization. In this approach usually DNA chips composed of a full library of oligonucleotides of a given length are used, but in principle it is possible to use another types of chips. Isothermic DNA chips, being one of them, when used for sequencing may reduce hybridization error rate. However, it was not clear if a number of errors following from subsequence repetitions is also reduced in this case. In this paper a method for estimating resolving power of isothermic DNA chips is described which allows for a comparison of such chips and the classical ones. The analysis of the resolving power shows that the probability of sequencing errors caused by subsequence repetitions is greater in the case of isothermic chips in comparison to their classical counterparts of a similar cardinality. This result suggests that isothermic chips should be chosen carefully since in some cases they may not give better results than the classical ones.

The paper deals with the problem of force and torque calculation for linear, cylindrical and spherical electromechanical converter.

The electromagnetic field is determined analytically with the help of separation method for each problem. The results obtained can be used as test tasks for electromagnetic field, force and torque numerical calculations. The analytical relations for torque and forces are also convenient for analysis of material parameters influence on electromechanical converter work.

Conceptions of analogue electronics circuit based on a multiple-input floating gate field-effect transistor MOS (MIFGMOS) have

been presented. The simple add and differential voltage amplifiers with one and two MIFGMOS transistors and multiple-input operational amplifiers with their application have been proposed. One of them was used for the realisation of a controlled floating resistor. Results of circuit simulations in SPICE programme using the simple substitute macromodel of MIFGMOS transistor have been shown.

The self-consistent optical-electrical-thermal-gain model of the oxide-confined edge-emitting diode laser has been used to simulate the room-temperature operation of the long-wavelength 1.3-µm quantum-dot (InGa)As/GaAs diode laser. The validityof the model has been verified using some experimental results for comparison. An impact of quantum-dot densityon laser operation characteristics as well as on temperature dependence of lasing threshold have been discussed.