The aim of the article is to analyse the spread and diffusion of socio-economic development in Poland in 2004-2016, while considering spatial aspects. Using the linear ordering method in the non-pattern version, a synthetic development measure for all municipalities in Poland was built based on a set of 77 features illustrating various socio-economic aspects, reduced to 25 features. For the measure constructed in this way, the convergence of the beta and sigma type has been examined, divided into 3 groups of municipalities (rural, urban and urban-rural), as well as in regional division. Using the methods of spatial econometrics, the occurrence of spatial effects was examined, in particular the attention was paid to the relationship between the processes of spreading development and spatial forms of diffusion of development. The analysis also allowed to determine the strength of local impacts of spatial connections between individual municipalities.

The Kuroshio Extension front (KEF) considerably influences the underwater acoustic environment; however, a knowledge gap persists regarding the acoustic predictions under the ocean front environment. This study utilized the high-resolution ocean reanalysis data (JCOPE2M, 1993–2022) to assess the impact of the KEF on the underwater acoustic environment. Oceanographic factors were extracted from the database using the Douglas-Peucker algorithm, and acoustic propagation characteristics were obtained using the Bellhop raytracing model. This study employed a backpropagation neural network to predict the acoustic propagation affected by the KEF. The depth of the acoustic channel axis and the vertical gradient of the transition layer of sound speed were identified as the fundamental factors influencing the first area of convergence, with correlations between the former and the distance of the first convergence zone ranging from 0.52 to 0.82, and that for the latter ranging from −0.42 to −0.7. The proposed method demonstrated efficacy in forecasting first convergence zone distances, predicting distances with less than 3 km error in >90% of cases and less than 1 km error in 68.61% of cases. Thus, this study provides a valuable predictive tool for studying underwater acoustic propagation in ocean front environments and informs further research.

Influence of magnetic field on parameters of normal detonation wave and cumulation process of cylindrical detonation wave in gaseous explosive mixture was examined. A review of applications of generalised Chester-Chisnell-Whitham (CCW) method used for analysis of implosion processes of detonation waves is presented.

A new observer of induction motor state variables is proposed in the paper. A nonlinearity of the main magnetic path is expressed as a function of a properly chosen parameter versus the position vector length. The value of the mutual inductance received n the identification algorithm is calculated exploiting the estimated values of the state variables. The coefficients appearing in the differential equations of the observer system are modified in each step of the algorithm on the basis of the calculated mutual inductance. The analysis of convergence of the identification algorithm is shown in this paper.

This article presents Nick Bostrom’s considerations of the future included in his book Superintelligence: Paths, Dangers, Strategies. Bostrom studies such issues as determining the hypothetic ways of attaining superintelligence, its nature and different aspects of this technology. He shows threats regarding such powerful systems, as well as constructing strategies of preventing undesirable activities of superintelligent beings. Bostrom’s input is an important part of present discussion concerning the development of artificial intelligence and its ethical problems.

We analysed the empirical importance of the capital flows in processes of economic convergence of the CEE region. We depart from reference net measures of capital flow reflecting the level of development of the financial system and focus on gross capital flow. Our econometric model is based on Seemingly Unrelated Regression Equation (SURE) elaborated by Arnold Zellner. This environment seems an alternative to standard panel regression, because it enables cross-country heterogeneity of parameters of interest (like pace of convergence). We tested several restrictions of the unconstrained SURE model, leading to simpler specifications that would allow for regional homogeneity of the role of a particular factor (like capital flows) in growth fluctuations and β-type convergence.

The aim of the paper is to measure and forecast concentration of regional development potential on a regional basis. The study covered 14 GUS features, which measure the development potential. The forecast, nominal values and processes’ dynamics were calculated for data from 2010 to 2020, using author made method. The study reveals that key factors determining the diversification of the distribution of the potential include the relation of large agglomerations to their regional surroundings. Therefore, we are dealing with growth poles with different impact levels. Since 2010, the process of concentrating potential in Poland has taken different directions. In poorly developed regions, we observe constant distribution values. Most regions, especially those with medium and high levels of economic development, are characterized by a dynamic increase in the level of concentration 5% to 6% annually. This means that the growth poles «move away» from their surroundings and strengthen their position. Simultaneously, they slightly reduce the distance to the strongest developed region in Poland (Mazowsze). By 2020, these trends will remain unchanged, however regions with a moderately low level of development will observe the fastest growth.

Iterative Learning Control (ILC) is a well-known method for control of systems performing repetitive jobs with high precision. This paper presents Constrained Output ILC (COILC) for non-linear state space constrained systems. In the existing literature there is no general solution for applying ILC to such systems. This novel method is based on the Bounded Error Algorithm (BEA) and resolves the transient growth error problem, which is a major obstacle in applying ILC to non-linear systems. Another advantage of COILC is that this method can be applied to constrained output systems. Unlike other ILC methods the COILC method employs an algorithm that stops the iteration before the occurrence of a violation in any of the state space constraints. This way COILC resolves both the hard constraints in the non-linear state space and the transient growth problem. The convergence of the proposed numerical procedure is proved in this paper. The performance of the method is evaluated through a computer simulation and the obtained results are compared to the BEA method for controlling non-linear systems. The numerical experiments demonstrate that COILC is more computationally effective and provides better overall performance. The robustness and convergence of the method make it suitable for solving constrained state space problems of non-linear systems in robotics.

This paper studies hydrodynamic and heat transfer performance of Al2O3/H2O nanofluid flowing through a Bessel-like converging pipe in laminar flow regime using the computational fluid dynamic approach. A parametric study was carried out on the effect of Reynolds number (300– 1200), convergence index (0-3) and nanoparticle concentration (0–3%) on the both hydrodynamic and thermal fields. The results showed the pressure drop profile along the axial length of the converging pipes is parabolic compared to the downward straight profile obtained in a straight pipe. Furthermore, an increase in convergence index, Reynolds number and nanoparticle concentration were found to enhance convective heat transfer performance. Also, a new empirical model was developed to estimates the average Nusselt number as a function of aforementioned variables. Finally, the result of the thermohydraulic performance evaluation criterion showed that the usage of Bessel-like converging pipes is advantageous at a low Reynolds number.

In the presented paper, two different meshing strategies are compared to show the accuracy advantage of properly constructed mesh. For this purpose, it was necessary to automatize simulation process, in order to perform a number of calculations without the necessity of user interaction. Later, a method of results extrapolation as well as a way of judging mesh quality are introduced for more throughout comparison of presented discretization strategies. The latter method, called grid convergence index, is also used to calculate probability range of accurate result. To conclude, outcomes of this study are in agreement with general opinon on pracitces for an accurate CFD result. Structured O-type mesh with refinement at wall boundaries (often referred to as “inflation layers”) performs better than simple free mesh.

The paper proposes a list of five „stylized facts”, regarded as the main trends with respect to the development of the global economy in the 20th c. The author’s main purpose is to answer the question whether, in the light of the contemporary growth theory and demographic forecasts, these trends are likely to continue unchanged also in the 21st c. Taking into account this theory and those forecasts, the paper offers forecasts of the average GDP per capita for both the countries of the Technology Frontier Area (TFA) and the catching-up countries. By these forecasts, the strong divergence trend of the last two centuries will be replaced by a strong convergence trend during the 21st c. Moreover, the global rate of growth of the per capita GDP will continue to be high in the first half of the current century, but strongly declining in the second half.

This paper provides analyses of the accuracy and convergence time of the PPP method using GPS systems and different IGS products. The official IGS products: Final, Rapid and Ultra Rapid as well as MGEX products calculated by the CODE analysis centres were used. In addition, calculations with weighting function of the observations were carried out, depending on the elevation angle. The best results were obtained for CODE products, with a 5-minute interval precision ephemeris and precise corrections to satellite clocks with a 30-second interval. For these calculations the accuracy of position determination was at the level of 3 cm with a convergence time of 44 min. Final and Rapid products, which were orbit with a 15-minute interval and clock with a 5 minute interval, gave very similar results. The same level of accuracy was obtained for calculations with CODE products, for which both precise ephemeris and precise corrections to satellite clocks with the interval of 5 minutes. For these calculations, the accuracy was 4 cm with the convergence time of 70 min. The worst accuracy was obtained for calculations with Ultra-rapid products, with an interval of 15 minutes. For these calculations, the accuracy was 10 cm with a convergence time of 120 min. The use of the weighting function improved the accuracy of position determination in each case, except for calculations with Ultra-rapid products. The use of this function slightly increased the convergence time, in addition to the CODE calculation, which was reduced to 9 min.

In order to overcome the shortcomings of the dolphin algorithm, which is prone to falling into local optimum and premature convergence, an improved dolphin swarm algorithm, based on the standard dolphin algorithm, was proposed. As a measure of uncertainty, information entropy was used to measure the search stage in the dolphin swarm algorithm. Adaptive step size parameters and dynamic balance factors were introduced to correlate the search step size with the number of iterations and fitness, and to perform adaptive adjustment of the algorithm. Simulation experiments show that, comparing with the basic algorithm and other algorithms, the improved dolphin swarm algorithm is feasible and effective.

The paper deals with the problems of designing observers and unknown input observers for discrete-time Lipschitz non-linear systems. In particular, with the use of the Lyapunov method, three different convergence criteria of the observer are developed. Based on the achieved results, three different design procedures are proposed. Then, it is shown how to extend the proposed approach to the systems with unknown inputs. The final part of the paper presents illustrative examples that confirm the effectiveness of the proposed techniques. The paper also presents a MATLAB® function that implements one of the design procedures.

This work presents an innovative shaft-lining solution which, in accordance with a patent of the Republic of Poland, allows successive, periodic leaching of excess rock salt migrating to the shaft opening. As is commonly known, all workings in rock salt strata are exposed to an increased convergence of sidewalls, making it very difficult to use shafts properly. Rocks migrating towards the shaft opening cause very high stress on the shaft liner. As a result, if the lining does not show substantial deformability, it fails. Lining failure due to insufficient deformability has been extensively described in the literature. Also, throughout the history of mining construction, a number of solutions have been proposed for different types of lining-deformability enhancement. For instance, the KGHM mining corporation applied a deformable steel lining – a solution used in the mining construction of galleries – along a 155-m-long section of the SW-4 shaft with diameters of 7,5 m that passes through a rock salt strata. At KGHM, the SW-4 shaft passes through a rock salt strata along a section of 155 m, in which a deformable enclosed steel lining was made. After several years, the convergence of shaft sidewalls stabilised at a rate of 0.5 mm/day. This enormous activity of the rock mass made it necessary to reconstruct the entire shaft section after only four years. According to further predictions, it will be necessary to reconstruct this section at least four times by 2045. This paper discusses in short form the underlying weaknesses of the technology in question.

As a solution to the problems mentioned above, the authors of this work present a very simple design of a shaft lining, called the tubing-aggregate lining, which utilises the leachability of salt rock massifs. The essential part of the lining is a layer of coarse aggregate set between the salt rock sidewall and the inner column of the tubing lining. One the one hand, coarse aggregate supports the salt rock sidewall and is highly deformable due to its compressibility, but on the other hand it allows water or low saturated brine to migrate and dissolve salt rock sidewalls.

This paper presents the first stage of works on this subject. Patent No. PL 223831 B had been granted before these works commenced.

The mine seals in coal mines with a good impact resistance and air tightness are mainly used to isolate abandoned mining areas from active workings. For one thing, it can prevent the leakage of harmful gases, such as toxic gas from abandoned areas. For another, once an underground mine explosion happens, it can effectively block the spread of the explosion between the abandoned mining areas and the active workings. Hence, it is of great significance to study the explosion-proof performance and mechanical properties of the mine seals. First of all, the effect of slotting on the stability of the seals in coal mines under explosion load was explored in this study. By numerical simulations, the mechanical response characteristics of the seals with or without cutting a slot under the explosion load were compared in detail. The results show that slotting improved the stress concentration at the contact surface of surrounding rock by transferring partial impact received by mine seals to the surrounding rocks, thus, to achieve the effect of buffering explosion impact. Besides, such effect will be enhanced with increasing cutting depth into rock, and will stabilize when the depth is 20 cm. On this basis, the mechanical properties and damage of the seals constructed by different materials (standard brick and #C40 concrete) under the explosion load were compared. It was found that once a slot was set, the maximum deformation of the concrete seal was reduced, while the maximum deformation of the brick seal increased. Since the non-deformability of the concrete seal is obviously stronger than that of the brick seal, with the impact resistance stronger than that of the brick seal, the concrete seal is more suitable for slotting. Moreover, the damage of the seals in underground coal mines under the strata ground pressure was studied; the results of which show that the damage state under the ground pressure can be divided into 3 levels, i.e. no damage, minor damage and rapid development of damage. Meanwhile, it was found that the prestressed structure formed by the ground pressure at the level of no damage can enhance the protective effect of the seals in coal mines. However, when the ground pressure was further developed, the seal itself was destroyed and the protective effect was lost. In addition, the influence of roof to floor moving convergence, a deformation parameter of the roadway, on the seals was also investigated. The results show that the ground pressure and roof-to-floor convergence act on the seals in coal mines in the same way, thus roof to floor moving convergence can replace the ground pressure to analyze other related mechanical properties of the seals in coal mines in the future researches.

The zero attraction affine projection algorithm (ZA-APA) achieves better performance in terms of convergence rate and steady state error than standard APA when the system is sparse. It uses l1 norm penalty to exploit sparsity of the channel. The performance of ZA-APA depends on the value of zero attractor controller. Moreover a fixed attractor controller is not suitable for varying sparsity environment. This paper proposes an optimal adaptive zero attractor controller based on Mean Square Deviation (MSD) error to work in variable sparsity environment. Experiments were conducted to prove the suitability of the proposed algorithm for identification of unknown variable sparse system.

In this work, two robust zeroing neural network (RZNN) models are presented for online fast solving of the dynamic Sylvester equation (DSE), by introducing two novel power-versatile activation functions (PVAF), respectively. Differing from most of the zeroing neural network (ZNN) models activated by recently reported activation functions (AF), both of the presented PVAF-based RZNN models can achieve predefined time convergence in noise and disturbance polluted environment. Compared with the exponential and finite-time convergent ZNN models, the most important improvement of the proposed RZNN models is their fixed-time convergence. Their effectiveness and stability are analyzed in theory and demonstrated through numerical and experimental examples.

The article aims to explain whether in 2004–2015 Poland experienced economic convergence between regions and counties (Polish: powiat), and whether this process occurred within the regions (Polish: województwo). Following Poland’s EU accession, the Polish policy became dominated by the polarization and diffusion concept of regional development, which may cause differences in the short term, while in the long run it may contribute not only to the increased efficiency of public funds allocation, but also to the elimination of disparities in growth levels. In the analysed period Poland experienced a process of economic divergence between the regions, only the years 2006–2008 saw a short-term reduction in regional disparities. On the other hand, a slow process of reducing economic inequalities between counties took place after 2004. It was, however, varied – a clear reduction in disparities occurred between the land counties (Polish: powiat ziemski) in an almost monotonic manner, whereas city counties (Polish: miasto na prawach powiatu) did not undergo any convergence. Within the regions, the process of economic convergence varied: in five regions, β-convergence was identified, and σ-convergence occurred in all the regions. The process of reducing disparities was significantly dependent on the development pathway of the region.

In the longwall exploitation system, the main gates are subject of the most intensive movements of the rock mass, where the proximity of the excavation front is a key factor. The paper presents the results of a research on the constants mb and s of Hoek-Brown failure criterion for the rocks surrounding the gallery: shale, sandy shale, coal and medium-grained sandstone, in relation to the distance to longwall face. The research comprised numerical modeling based on convergence monitoring records. The convergence measurements were carried out on three stations in a selected maingate in a coal mine from Upper Silesia Coal Basin near Jastrzębie-Zdrój, concurrently with changing distance to the longwall face. The measured were the width, the height and the heave of the floor of the gate. The measurements showed that the convergence at the longwall-maingate crossing was 1.5-3 times greater than in the locations much further from the longwall face. It was demonstrated that this effect was due to continuously changing properties of the rock-mass surrounding the gallery that can be expressed as decreasing empirical parameters mb i s of Hoek-Brown’s criterion. These parameters are decreasing exponentially together with the distance to the longwall face The consistency between the theoretical and factual curve varies between 70% to 98%. The change of each of the parameters can be described by general equation P = a· exp(–b·d), where a, b are constants, and d is the distance to the excavation face. The authors highlight that during the measurements period the horizontal stress was 1.45 to 1.61 times greater than the concurrent vertical stress. The so high horizontal stress causes heave of unsupported gallery floor which is commonly observed in the mines in Silesia.

In this article we construct a finite-difference scheme for the three-dimensional equations of the atmospheric boundary layer. The solvability of the mathematical model is proved and quality properties of the solutions are studied. A priori estimates are derived for the solution of the differential equations. The mathematical questions of the difference schemes for the equations of the atmospheric boundary layer are studied. Nonlinear terms are approximated such that the integral term of the identity vanishes when it is scalar multiplied. This property of the difference scheme is formulated as a lemma. Main a priori estimates for the solution of the difference problem are derived. Approximation properties are investigated and the theorem of convergence of the difference solution to the solution of the differential problem is proved.

On January 14, 2011, Zayn al-‘Ābidīn Bin ‘Alī resigned, left Tunisia and took refuge in Saudi Arabia following the revolts born in Sīdi Būzīd after the suicide of Bū-‘Azīzī. The Arab Spring in Tunisia was not a popular uprising perpetrated by the lower class and the unemployed young people: the committees of the lawyers and the magistrates who joined the protests, proved the active participation of the middle class. However, the Revolution did not alleviate the popular unrest, and it did not reduce the social imbalances. The diastratic varieties, already existing before the Revolution, are the linguistic reflection of the social situation. After 2011 the main actors of the protests, proceeding from the lowest and youngest class, came back to the Ḥū ma, the ghetto, in which anger and frustration flourish. The description of the life in the Ḥūma, has become the main topic of many songs written by the new generation of Tunisian artists who sing in the slang of the lower class. Despite they proceed from the upper class, they have become the spokesmen of the malaise that hovers in the poor neighborhoods. Guerrero (2012) analysed linguistically Rāyǝs lǝ-Blād, a song by the Tunisian rapper El Général, appeared on internet on February 8th, 2011, few days before the escape of Bǝn ԑAlī. Rāyǝs lǝ-Blād is an example of the artistic denunciation of the political oppression and the social degradation. The songs of artists such as Kafon, Hamzaoui Med Amin and Balti, which appeared after the Revolution instead, are not acts of protest, they just represent the ordinary life of the ūlād ǝl-Ḥūma in the ghetto. What linguistic dynamics are put in place by these singers? After a historical-etymological reconstruction related to the word Ḥūma, it will be shown how this group of artists practiced, on the one hand, the divergence with respect to the prestigious variety of the capital, on the other, the convergence towards the language of the tunisian poorest class.

The paper is intented to show a new, state space, discrete, non integer order model of a one-dimensional heat transfer process. The proposed model derives directly from time continuous, state space model and it uses the discrete Grünwald-Letnikov operator to express the fractional order difference with respect to time. Stability and spectrum decomposition for the proposed model are recalled, the accuracy and convergence are analyzed too. The convergence of the proposed model does not depend on parameters of heater and measuring sensors. The dimension of the model assuring stability and predefined rate of convergence and stability is estimated. Analytical results are confirmed by experiments.