Bulletin of the Polish Academy of Sciences. Technical Sciences
A device was designed and constructed for direct observations of crack growth from notch or form Vickers indent made on the beam bent in a typical testing machine. The device, consisting of horizontal light microscope coupled with CCD camera, is fitted to ZWICK 1446 testing machine by the system of elevator stages driven by stepping motors. This enables precise movements of objective in x, y, z-direction,...
The joinability of materials that show significant difference in their physical and chemical properties is a function directly proportional to the absolute number of Gibbs free energy negative value and to the values of the diffusion coefficients of the ions or atoms of couple of materials under joining, and inversely proportional to the difference of their thermal expansion coefficients. The paper...
The paper presents the results of investigations on particulate ceramic composites with the tetragonal zirconia polycrystalline (TZP) matrix. The WC, CrxCy and TiC particles were used as additives. The possibility of a chemical reaction in these systems was taken into account. Stresses caused by coefficient of thermal expansion mismatch of composite constituents were estimated. Phase composition and...
The development of biological organisms is coded in appropriate algorithms of DNA. At the conceptual level this development has an embryonic character; on the operational its control is based on the exchange of messages between cells. The article presents a comparison of these biological solutions with the corresponding structures and realization of algorithms used in technical informatic systems.
Necessary and sufficient condition for stability of convex combination of symmetrizable matrices is given. Necessary and sufficient condition for stability of an interval matrix, symmetrizable by diagonal matrix is proposed.
In this paper a concept of chemical recognition dynamics is introduced. The concept is based on the definition of the molecular recognition. An element of this definition, the range of selection set indicates tasks for chemical recognition dynamics. Chemical dynamics accentuates dynamics of processes near transition states along reaction path. Chemical recognition dynamics is viewed to be part of...
The paper deals with the problem of digital circuit design based on the current-mode gates - novel digital elements operating with a constant, continuous power supply current. The purpose is the provision of a high level noise immunity of chips which contain both analog and digital circuits. The logical properties and several identities of the current-mode logic and some expressions for a conversion...
The paper is aimed on 2-D models for fractal linear structures composed of identical passive elements and connected into the Sierpiński triangle. A new approach for evaluation of the distribution of appropriate signals within the whole structure is established. The efficiency of the method is demonstrated and well proved. Distinguished properties of the established distribution are demonstrated. Illustrative...
A new extended Roesser type model is introduced and its solution is derived. Sufficient conditions are established under which a singular 2D general model can be reduced to standard 2D general models. Solution to the new model is also derived.
The nature of speech signal is very complicated, that causes that its visualization and further analysis, without some initial pre-processing, is very complicated and doesn't always bring the desired effects. Speech signal in most cases is represented by videograms. The analysis of these forms of signal visualisation is not easy because of difficulties in their interpretation. In this article the...
The paper presents parallel versions of a branch and bound algorithm for scheduling jobs in the two-machine flow shop were machines have some periods of limited availability. A problem of minimizing makespan in such a flow shop is NP-hard in the strong sense. Moreover, no polynomial time heuristic with finite relative error exists for the problem unless P = NP. One of the standard approaches for solving...
This paper generalizes the interpolation problem with multiplicities to the case of tangential interpolation, i.e., there are imposed interpolation conditions on the matrix B(s) = S(s)A(s) and its deratives at the points s1,..., sn with A(s) being an arbitrary matrix and S(s) being a bounded real matrix. Assuming that the corresponding Nevanlinna-Pick matrix is positive definite, the interpolation...
In this paper steady transonic flows are considered. A modelization and a functional approach are proposed. In order to constrain the shock waves to appear, a jump inequality, involving the tangential component of the mass flux is introduced. A new solution procedure is given by minimizing a functional acting on a compact set.
This paper presents a new, non-blocking switching element design for computer networks, which is called the RS (Ring Space-division) switch. The idea of this new design is the combination of the space-divison switching techniques together with the ring topology. The RS switch is distinguished by its cross-points saving, short and fixed data-path length, high multicast capability, and complete redundancy...
A new accurate, physical, continuous, and simple DC MOSFET model for short-channel devices down to submicron channel lengths is presented in this paper for the simulation of VLSI circuits. The proposed model is based on the Charge-Sheet Approximation (CSA) and describes efficiently the I-V characteristics from subthreshold to strong inversion region as well as from the linear to the saturation region...
A new approach to valuation of bonds under the default risk conditions, based on the concept of the investors' two-factor utility function is proposed. The first factor describes the expected average return from the risky investments, while the second - the worst case return. As a class of risky securities the so called catastrophe bonds are considered. It is assumed that depending on the structure...
The paper deals with the problem of the best relation between the investment rate of return and investment safety. Safety is defined as the notion opposite to the investment risk. The principle of optimum ratio safety / return says that the ratio should be equal investor's sensitivity to safety over the marginal cost of substitution (safety for return). Three applications of the principle are given...
The problem considered in the paper is formulated as follows. Given a finite set of elements called alternatives, set of properties or attributes and a set of experts. Their task is to estimate the importance of alternatives under consideration wit h respect to the chosen criterion, i.e. to evaluate estimates of alternative weights. Experts can be asked to give their judgements on all the alternatives...
The paper extends the main result of [1], that is, the construction of a K-immunization strategy with the highest convexity to a more general setting by dropping the key assumption of [1] stating that interest rate shocks ht to occur in a near future are proportional to the values of spot rates Yt plus 1, e.g. the condition (4) holds. Here, the interest rate shifts ht are allowed to be of the more...
We consider the combinatorial optimization problem in the following form: min{EEF c(e) : F E F} -( formula), where for some finite set E, c = (c(e), e E E) E R+ (formula) is a vector of weights of elements of E, and F C 2E (formula) is a given family of feasible subsets. We assume that the set F is fixed, but the weights of elements belonging to some given subset X C E may vary. The accuracy function...