Acoustic signal is more and more frequently used to diagnose machines operated in industrial conditions where installation of sensors is hindered. Impact of background noise seems to be the major problem as part of analysis of such signal. In most cases of industrial environments, background level is high; thus, it prevents against concluding as per standard methods that have been used in diagnostic testing. This study specifies the problem related to diagnosing machines operated under variable loads. Synchronous methods are used for diagnosing these types of machines, those include synchronisation of diagnostic signal with revolutions of the diagnosed machine. For the purpose of this study an acoustic signal was used as the diagnostic signal. Application of the synchronous method (order analysis) enables eliminating an impact of background noise derived from other sources. This study specifies application of acoustic signal to diagnose planetary gear in laboratory testing rig in order to discover damages at early stage of degradation. This method was compared with the method basing on measurement of vibrations.
The use of fractional-order calculus for system modeling is a good alternative to well-known classic integer-order methods, primarily due to the precision with which the modeled object may be mapped. In this study, we created integer and fractional discrete models of a real object – a highspeed brushless micro-motor. The accuracy of the models was verified and compared.
Given a linear discrete system with initial state x0 and output function yi , we investigate a low dimensional linear systemthat produces, with a tolerance index ǫ, the same output function when the initial state belongs to a specified set, called ǫ-admissible set, that we characterize by a finite number of inequalities. We also give an algorithm which allows us to determine an ǫ-admissible set.
The global stability of positive continuous-time standard and fractional order nonlinear feedback systems is investigated. New sufficient conditions for the global stability of these classes of positive nonlinear systems are established. The effectiveness of these new stability conditions is demonstrated on simple examples of positive nonlinear systems.
The article introduces a new proposal of a defuzzification method, which can be implemented in fuzzy controllers. The first chapter refers to the origin of fuzzy sets. Next, a modern development based on this theory is presented in the form of ordered fuzzy numbers (OFN). The most important characteristics of ordered fuzzy numbers are also presented. In the following chapter, details about the defuzzification process are given as part of the fuzzy controller model. Then a new method of defuzzification is presented. The method is named center of circles intersection (CCI). The authors compare this method with a similar geometric solution: triangular expanding (TE) and geometric mean (GM). Also, the results are compared with other methods such as center of gravity (COG), first of maxima (FOM) and last of maxima (LOM). The analysis shows that the proposed solution works correctly and provides results for traditional fuzzy numbers as well as directed fuzzy numbers. The last chapter contains a summary, in which more detailed conclusions are provided and further directions of research are indicated.
In the Polish spatial planning law one of basic principles is to preserve spatial order. However, the analysis of the law and its implementation show, that instead of spatial order, overall circumstances promote disorder. The analysis covers the law adopted in 2018, which aimed at boosting the development of housing. Findings show, that the new law may rather promote chaos in urban space. One of the drawbacks is undermining of the spatial order by creating the possibility of adopting resolutions pertaining to housing and accompanying services, that are contradictory to provisions of master plans.
The paper is concerned with the most fundamental compositional divide to be found in lyrical discourse, consisting in that the latter one is normally split into an empirical part, presenting the author’s concrete experience, and a focal part, where the author discovers some signifi cant truth or/and changes her attitude towards the world. It is claimed in the paper that, more generally, one of the specifi c linguistic properties of focal fragments is their higher and/or specially underscored informativity, and, in particular, one of the means recruited to emphasize it is inverted word order.
The article refers to the urban sprawl in Poland. Its objectives are: (1) analysis of relations between negative eff ects, (2) presentation negative effects on transport and energy consumption and on spatial order, (3) analysis of ways of counteracting negative processes including conditions (especially restrictions) on the use of this ways and their effectiveness. The methods used were: observation, literature analysis and logical analysis. Driving forces are heading towards further suburbanization, stopping of which is considered impossible. Orientation of the processes more closely to spatial order is very difficult. There are proper and legal solutions for this, but there are barriers to their use, such as: the lack of awareness and motivation of local authorities and the political conditions that discourage more restrictive regulation.
In the presented paper we discuss pure versions of pushdown automata that have no extra non-input symbols. More specifically, we study pure multi-pushdown automata, which have several pushdown lists. We restrict these automata by the total orders defined over their pushdowns or alphabets and determine the accepting power of the automata restricted in this way. Moreover, we explain the significance of the achieved results and relate them to some other results in the automata theory.
The paper presents findings of a research project aimed at a reconstruction of the dynamics of biographical experiences of some of those categories of the Polish society’s members whose educational and professional careers have been shaped by the systemic transformation after 1989. The text is an attempt to delineate analytical guidelines for grasping how some components of three types of social order, conceived in terms of premodernity, modernity and postmodernity, interpenetrating each other in the contemporary life of the society, impact its members’ biographical experiences on the level of work, social ties and identity.
In the paper, problem of proper tuning of second-order Reduced Active Disturbance Rejection Controller (RADRC2) is considered in application for industrial processes with significant (but not dominant) delay time. For First-Order plus Delay Time (FOPDT) and Second-Order plus Delay Time (SOPDT) processes, tuning rules are derived to provide minimal Integral Absolute Error (IAE) assuming robustness defined by gain and phase margins. Derivation was made using optimization procedure based on D-partition method. The paper also shows results of comprehensive simulation validation based on examplary benchmark processes of more complex dynamics as well as final practical validation. Comparison with PID controller shows that RADRC2 tuned by the proposed rules can be practical alternative for industrial control applications.
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