As it is found in the related published literatures, the transfer function (TF) evaluation method is the most feasible method for detection of winding mechanical faults in transformers. Therefore, investigation of an accurate method for evaluation of the TFs is very important. This paper presents three new indices to compare the transformer TFs and consequently to detect the winding mechanical faults. These indices are based on estimated rational functions. To develop the method, the necessary measurements are carried out on a 1.3 MVA transformer winding, under intact condition, as well as different fault conditions (axial displacement of winding). The obtained results demonstrate the high potential of proposed method in comparison with two other well-known indices. Additionally, two important methods for describing TFs by rational functions are studied and compared in this paper.
The main goal of this paper is to analyze the matching function in the Polish labour market in 1994‒2008. Matching function is the relationship between outflows from unemployment to employment and the number of unemployed persons and vacancies as well as other variables which affect the efficiency of the matching process directly or indirectly. Such matching function in its augmented form is estimated here for Poland with the use of data from register of unemployed persons.
The results indicate that there is a statistically stronger impact of the unemployed than vacancies on new hires. Furthermore, the institutional conditions of the labour market, the structure of the unemployed and the participants of active labour market programs (ALMP) play a role in the matching process.
In the paper, the variation of the intensity of the geomagnetic field force is analysed in time and space. For the research, the data from measurements of the intensity of the geomagnetic field force at four airports (Kaunas, Klaip˙eda, Palanga andVilnius) and 6 geomagnetic field repeat stations aswell as the data from Belsk Magnetometric Observatory (Poland) were used. For the data analysis, the theory of covariance functions was applied. The estimates of the cross-covariance functions of the measured intensity of the geomagnetic field force or the estimates of auto-covariance functions of single data were calculated according to the random functions created from the force intensity measurement data arrays. The estimates of covariance functions were calculated upon varying the quantization interval on the time scale and applying the software created using Matlab package of procedures. The impact of radars of airports on the intensity of geomagnetic field variation and on changes of their covariance functions was established.
This paper presents control method for multiple two-wheeled mobile robots moving in formation. Trajectory tracking algorithm from [7] is extended by collision avoidance, and is applied to the different type of formation task: each robot in the formation mimics motion of the virtual leader with a certain displacement. Each robot avoids collisions with other robots and circular shaped, static obstacles existing in the environment. Artificial potential functions are used to generate repulsive component of the control. Stability analysis of the closed-loop system is based on Lyapunov-like function. Effectiveness of the proposed algorithm is illustrated by simulation results.
The article presents the process of functional changes in the area of the Metropolis of Poznań, i.e. 22 communes belonging to the Metropolia Poznań Association. The process was examined on the basis of changes in the employment structure and spatially different tendencies and segregation in the scope of dominant functions.
B a c k g ro u n d: Arterial hypertension (HTN) ranks among the most widespread chronic illnesses that affect adults in industrialized societies. The main goal of this study was to describe the control (inhibition) processes among HTN patients, and to evaluate the dynamics of brain activity while the patients were engaged in tasks measuring the cognitive aspect of self-control.
P a r t i c i p a n t s a n d p ro c e d u re: A set of neuropsychological tests (California Verbal Learning Test, Color Trails Test, The Trail Making Test, Controlled Oral Word Association Test), and a fMRI Stroop test (rapid event design) were administered to 40 persons (20 HTN patients and 20 controls). Groups were matched in terms of age, sex, education, smoking history, and waist-to-hip ratio.
R e s u l t s: As revealed by fMRI, the HTN patients demonstrate left-hemisphere asymmetry in inhibitory processes. Also around 90% of patients had problems when completing tasks which rely on verbal and graphomotor aspects of self-control.
C o n c l u s i o n s: The results suggest that both cerebral hemispheres must interact correctly in order to provide successful executive control. The deficiencies in control and executive functioning, which were observed among the patients, prove that HTN negatively affects brain processes that control one’s cognitive activity.
In this paper, it has been shown that any measuring process can be modeled as a process of sampling of signals. Also, a notion of a special kind of functions, called here functions with attributes, has been introduced. The starting point here, in the first of the above themes, is an observation that in fact we are not able to measure and record truly continuously in time any physical quantity. The measuring process can be viewed as going stepwise that is in steps from one instant to another, similarly as a sampling of signals proceeds. Therefore, it can be modeled as the latter one. We discuss this in more detail here. And, the notion of functions with attributes, we introduced here, follows in a natural way from the interpretation of both the measuring process as well as the sampling of signals that we present in this paper. It turns out to be useful.
This article presents methods and algorithms for the computation of isogenies of degree ℓn. Some of these methods are obtained using recurrence equations and generating functions. A standard multiplication based algorithm for computation of isogeny of degree ℓn has time complexity equal to O(n2 M (n log n)), where M(N) denotes the cost of integers of size N multiplication. The memory complexity of this algorithm is equal to O (n log (n log (n))). In this article are presented algorithms for:
where optimality in this context means that, for the given parameters, no other strategy exists that requires fewer operations for computation of isogeny.
Also this article presents a method using generating functions for obtaining the solutions of sequences (um) and (cm) where cm denotes the cost of computations of isogeny of degree ℓum for given costs p; q of ℓ-isogeny computation and ℓ-isogeny evaluation. These solutions are also used in the construction of the algorithms presented in this article.
In search for a path of development, some communities face internal factors deeply influencing the choice of development strategy. Such factor would be an environmental protection of the territory, as it may crucially limit industrial activity. Narol community, located in southeastern Poland, near the Ukrainian border (Podkarpackie Voivodeship), has landscape protection of several levels covering 100% of the territory, so the possible development could not consist on industrial investments. On the other hand the concerned region, Roztocze, is a recognized touristic area, but Narol was always rather out of its main tourists trails. Nevertheless its assets (nature reserves, landscape and monuments), would predestine Narol for a touristic destination. But, considering strong competition in the region, the distinguishing feature would be of importance. The municipality had recognized cultural tourism as a way Narol could adopt, and has started several activities aiming to transform Narol into a cultural centre of the region. This paper presents the study case of Narol municipality’s activities in the context of transferring neglected heritage into an activated agent of development – resulting in social and economic growth. Its’ aim is to research (based on the Narol example) a place of local heritage assets in development process: if, and how they can be used to increase community’s sustainable growth.
In this paper we present a copula-based model for a binary and a continuous variable in a time series setup. Within this modeling framework both marginals can be equipped with their own dynamics whereas the contemporaneous dependence between both processes can be flexibly captured via a copula function. We propose a method for testing the goodness-of-fit of such a time series model using probability integral transforms (PIT). This verification procedure allows not only a verification of the goodness-of-fit of the estimated marginal distribution for a continuous variable but also the conditional distribution of a continuous variable given the outcome of its binary counterpart (i.e. the adequacy of the copula choice). We test the model on an empirical example: investigating the relationship between trading volume and the indicators of arbitrarily ’large’ price movements on the interbank EUR/PLN spot market.